Jeff's DIY

Advice on doing your own diagnosis and repair


Advice from the book Can I Do It Myself?


Real-time and Emergency Auto Diagnostics

The advent of Bluetooth technology and smartphones have allowed for inexpensive automotive computer scanning. I recommend this for people that travel long distances, as there are many diagnostic codes that indicate malfunctions that are relatively harmless and can be repaired when convenient; and having that knowledge will provide you with peace of mind to continue on a trip. For about $20 USD, you can get a Bluetooth-enabled interface to the standard OBDII port on your car or truck. There are many free apps you can install on your smartphone to pair your phone app to the interface and connect to your car's computer. Once connected, there are several modes available. The modes I use are reading and clearing diagnostic codes as well as streaming sensor data. I often do this on the road, if the Malfunction Indicator Light (MIL), otherwise known as the "Check Engine" light, illuminates. I do this even if there are no symptoms of a malfunction, because a malfunction could strand me in the middle of nowhere or possibly damage my car if left unresolved. There are now commercial products that provide similar capabilities and connect you to a help center or send data on the use of the car, but these require a cell tower connection and monthly service fee. In this chapter, I will provide information on how to set up this capability for yourself and use it to make decisions on the road. If you happen to have a cell connection, you can also contact a mechanic to get a better diagnosis or to lookup more info online. Note that The OBD II diagnostic code set required by law is supplemented by many auto manufacturers with additional codes. I cannot provide info on all of these, but most of them are redundant with the standard set that I will cover here.

Note that I have already explained a bit about interfacing your car's computer in the previous chapter in the section on "Check Engine Light On--What Do I Check?" If your car is a model year 1996 or later, it is required to have an OBD II data port. The data port is usually located under the dashboard on the driver's side. On some imports, it is hidden behind a dashboard panel. Make sure to find yours before you buy an interface for it. To buy an interface, you may be able to find one at your local auto parts store or even at WALMART. The one I have looks like the picture on the right below, next to a picture of the data port on a typical car. I saw one for less than $4 at eBay. To find one online, google "OBD II Bluetooth."

OBD connectorOBD II communication adapter

 

Once you have the interface, go to the app store on your smartphone to find a free OBD II Bluetooth app. As with any Bluetooth device, you must pair the device with your smartphone. The device draws power from the data port. If the device does not light or otherwise respond when plugged into the port, check your fuses. The port is often on the same circuit as the auxiliary power ports or cigarette lighters in your car. Your car owner's manual should identify the fuse to be checked. Once the port is on, turn your ignition key on. The car does not have to be running to access the computer, but the key has to be on to power it up. With the device paired and the key on, the app should connect to the computer or ECM. It may say "connected to ECM" or "connected to ECU." Sometimes you have to adjust the app settings to get it to connect, depending on the app. Test yours at home-before you need it. If it is difficult to connect, you might want to write down what worked and keep that note with the device in your glovebox. Once the device connects to the computer, you can read the diagnostic trouble codes (DTCs), clear the codes, or read sensor data. The last option is useful when you have a problem that you think might be caused by a sensor malfunction. It can be used even if the MIL is not lit. For example, I recently used my device to verify that my mass airflow sensor was providing good data to the computer. Other sensors I often check using the device are the oxygen sensors, throttle position sensor (TPS), and manifold absolute pressure (MAP) sensor.

In the table below, I list all of the standard OBD II DTCs along with my recommendation for what to do when you extract these codes from your computer on the road. If you have multiple codes, write them all down and check them all against this table. You may also want to check the computer 1for pending codes. These are codes that indicate a malfunction that the computer has recognized but has not yet declared as a true malfunction. This mode is used by the computer for malfunctions that often heal themselves. The computer will not set these codes outright and light the MIL until the malfunction repeats for two or more run cycles.


DTC

Title

Recommendation

P0100

Mass or Volume Air Flow Circuit Malfunction

These codes refer to the airflow sensor, which is located between the air filter and engine. Most cars can run without this sensor, but the engine may cough or run rich. If the car runs ok, it is safe to drive short distances or until you can reach safety.

P0101

Mass or Volume Air Flow Circuit Range/Performance Problem

P0102

Mass or Volume Air Flow Circuit Low Input

P0103

Mass or Volume Air Flow Circuit High Input

P0104

Mass or Volume Air Flow Circuit Intermittent

P0105

Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction

These codes refer to the intake manifold pressure sensor, which is usually attached to the intake manifold near the top of the engine. Most cars can run without this sensor, but the engine may cough or run rich. If the car runs ok, it is safe to drive short distances or until you can reach safety.

P0106

Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem

P0107

Manifold Absolute Pressure/Barometric Pressure Circuit Low Input

P0108

Manifold Absolute Pressure/Barometric Pressure Circuit High Input

P0109

Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent

P0110

Intake Air Temperature Circuit Malfunction

These codes refer to the air temperature sensor, which is located between the air filter and engine. Most cars can run without this sensor, but the engine may cough or run rich. If the car runs ok, it is safe to drive short distances or until you can reach safety.

P0111

Intake Air Temperature Circuit Range/Performance Problem

P0112

Intake Air Temperature Circuit Low Input

P0113

Intake Air Temperature Circuit High Input

P0114

Intake Air Temperature Circuit Intermittent

P0115

Engine Coolant Temperature Circuit Malfunction

These codes refer to the coolant temperature sensor, which is usually located on the engine near one of the large radiator hoses. Most cars can run without this sensor, as long as the engine does not overheat. If the car runs ok and the engine does not seem hot, it is safe to drive short distances or until you can reach safety. If the engine gets hot, it could be damaged severely. If you drive the engine hot, expect to be stranded and to destroy the engine.

P0116

Engine Coolant Temperature Circuit Range/Performance Problem

P0117

Engine Coolant Temperature Circuit Low Input

P0118

Engine Coolant Temperature Circuit High Input

P0119

Engine Coolant Temperature Circuit Intermittent

P0120

Throttle/Pedal Position Sensor/Switch "A" Circuit Malfunction

Most cars will not run with this code. This sensor is usually attached to the accelerator pedal. The engine uses this sensor to control the throttle. If you drive with this malfunction, you can lose control of the engine rpms.

P0121

Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance Problem

P0122

Throttle/Pedal Position Sensor/Switch "A" Circuit Low Input

P0123

Throttle/Pedal Position Sensor/Switch "A" Circuit High Input

P0124

Throttle/Pedal Position Sensor/Switch "A" Circuit Intermittent

P0125

Insufficient Coolant Temperature For Closed Loop Fuel Control

This code indicates the engine is too cold to properly control the air/fuel mixture. Most cars can run with this code, but the engine may cough or run rich. If the car runs ok, it is safe to drive short distances or until you can reach safety.

P0126

Insufficient Coolant Temperature For Closed Loop Fuel Control

P0128

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

P0130

O2 Circuit Malfunction (Bank #1 Sensor #1)

Most engines will run with O2 sensor malfunctions. Depending on the particular malfunction, the engine may run fine or could run rich or lean and perhaps even cough. If the engine runs ok, it is safe to drive short distances. Some cars may revert to limp mode if certain O2 sensor malfunctions occur. Limp mode is intended to allow you to drive to a mechanic for safety without harming the engine. In most cases, an engine in limp mode still has significant performance. If the engine runs poorly, you may want to call for a tow truck.

P0131

O2 Sensor Circuit Low Voltage (Bank #1 Sensor #1)

P0132

O2 Sensor Circuit High Voltage (Bank #1 Sensor #1)

P0133

O2 Sensor Circuit Slow Response (Bank #1 Sensor #1)

P0134

O2 Sensor Circuit No Activity Detected (Bank #1 Sensor #1)

P0135

O2 Sensor Heater Circuit Malfunction (Bank #1 Sensor #1)

P0136

O2 Sensor Circuit Malfunction (Bank #1 Sensor #2)

P0137

O2 Sensor Circuit Low Voltage (Bank #1 Sensor #2)

P0138

O2 Sensor Circuit High Voltage (Bank #1 Sensor #2)

P0139

O2 Sensor Circuit Slow Response (Bank #1 Sensor #2)

P0140

O2 Sensor Circuit No Activity Detected (Bank #1 Sensor #2)

P0141

O2 Sensor Heater Circuit Malfunction (Bank #1 Sensor #2)

P0142

O2 Sensor Circuit Malfunction (Bank #1 Sensor #3)

P0143

O2 Sensor Circuit Low Voltage (Bank #1 Sensor #3)

P0144

O2 Sensor Circuit High Voltage (Bank #1 Sensor #3)

P0145

O2 Sensor Circuit Slow Response (Bank #1 Sensor #3)

P0146

O2 Sensor Circuit No Activity Detected (Bank #1 Sensor #3)

P0147

O2 Sensor Heater Circuit Malfunction (Bank #1 Sensor #3)

P0150

O2 Sensor Circuit Malfunction (Bank #2 Sensor #1)

P0151

O2 Sensor Circuit Low Voltage (Bank #2 Sensor #1)

P0152

O2 Sensor Circuit High Voltage (Bank #2 Sensor #1)

P0153

O2 Sensor Circuit Slow Response (Bank #2 Sensor #1)

P0154

O2 Sensor Circuit No Activity Detected (Bank #2 Sensor #1)

P0155

O2 Sensor Heater Circuit Malfunction (Bank #2 Sensor #1)

P0156

O2 Sensor Circuit Malfunction (Bank #2 Sensor #2)

P0157

O2 Sensor Circuit Low Voltage (Bank #2 Sensor #2)

P0158

O2 Sensor Circuit High Voltage (Bank #2 Sensor #2)

P0159

O2 Sensor Circuit Slow Response (Bank #2 Sensor #2)

P0160

O2 Sensor Circuit No Activity Detected (Bank #2 Sensor #2)

P0161

O2 Sensor Heater Circuit Malfunction (Bank #2 Sensor #2)

P0162

O2 Sensor Circuit Malfunction (Bank #2 Sensor #3)

P0163

O2 Sensor Circuit Low Voltage (Bank #2 Sensor #3)

P0164

O2 Sensor Circuit High Voltage (Bank #2 Sensor #3)

P0165

O2 Sensor Circuit Slow Response (Bank #2 Sensor #3)

P0166

O2 Sensor Circuit No Activity Detected (Bank #2 Sensor #3)

P0167

O2 Sensor Heater Circuit Malfunction (Bank #2 Sensor #3)

P0170

Fuel Trim Malfunction (Bank #1)

Fuel mixture malfunctions can cause damage to your car, if you drive extensively while they exist. However, if the car runs OK, it can be driven for 10-20 miles without significant damage.

P0171

System Too Lean (Bank #1)

P0172

System Too Rich (Bank #1)

P0173

Fuel Trim Malfunction (Bank #2)

P0174

System Too Lean (Bank #2)

P0175

System Too Rich (Bank #2)

P0176

Fuel Composition Sensor Circuit Malfunction

P0177

Fuel Composition Sensor Circuit Range/Performance

P0178

Fuel Composition Sensor Circuit Low Input

P0179

Fuel Composition Sensor Circuit High Input

P0180

Fuel Temperature Sensor "A" Circuit Malfunction

If the vehicle runs with this code, it is likely the sensor is malfunctioning. Fuel that is too cold or too hot will not harm the engine, but it may prevent starting or cause hesitation.

P0181

Fuel Temperature Sensor "A" Circuit Range/Performance

P0182

Fuel Temperature Sensor "A" Circuit Low Input

P0183

Fuel Temperature Sensor "A" Circuit High Input

P0184

Fuel Temperature Sensor "A" Circuit Intermittent

P0185

Fuel Temperature Sensor "B" Circuit Malfunction

P0186

Fuel Temperature Sensor "B" Circuit Range/Performance

P0187

Fuel Temperature Sensor "B" Circuit Low Input

P0188

Fuel Temperature Sensor "B" Circuit High Input

P0189

Fuel Temperature Sensor "B" Circuit Intermittent

P0190

Fuel Rail Pressure Sensor Circuit Malfunction

Low fuel pressure will cause the engine to run lean or not at all, but it is not likely to damage the vehicle. If the vehicle runs, drive to safety but no farther, as the condition may worsen and leave you stranded. If the vehicle does not run, check your fuel level—you may be out of fuel.

P0191

Fuel Rail Pressure Sensor Circuit Range/Performance

P0192

Fuel Rail Pressure Sensor Circuit Low Input

P0193

Fuel Rail Pressure Sensor Circuit High Input

P0194

Fuel Rail Pressure Sensor Circuit Intermittent

P0195

Engine Oil Temperature Sensor Malfunction

If the vehicle is not overheating, the likely cause of these codes is sensor or wiring failure. The vehicle is safe to drive as long as it is not overheating.

P0196

Engine Oil Temperature Sensor Range/Performance

P0197

Engine Oil Temperature Sensor Low

P0198

Engine Oil Temperature Sensor High

P0199

Engine Oil Temperature Sensor Intermittent

P0200

Injector Circuit Malfunction

Injector malfunctions will usually cause the engine to miss. A miss caused by these codes is not likely to harm the vehicle, but it may be difficult to drive, depending on the size of the engine. If the engine runs ok or only misses a little, it is ok to drive it to safety.

P0201

Injector Circuit Malfunction — Cylinder #1

P0202

Injector Circuit Malfunction — Cylinder #2

P0203

Injector Circuit Malfunction — Cylinder #3

P0204

Injector Circuit Malfunction — Cylinder #4

P0205

Injector Circuit Malfunction — Cylinder #5

P0206

Injector Circuit Malfunction — Cylinder #6

P0207

Injector Circuit Malfunction — Cylinder #7

P0208

Injector Circuit Malfunction — Cylinder #8

P0209

Injector Circuit Malfunction — Cylinder #9

P0210

Injector Circuit Malfunction — Cylinder #10

P0211

Injector Circuit Malfunction — Cylinder #11

P0212

Injector Circuit Malfunction — Cylinder #12

P0213

Cold Start Injector #1 Malfunction

A cold start injector malfunction may prevent starting. If the vehicle starts, it is safe to drive it to safety.

P0214

Cold Start Injector #2 Malfunction

P0215

Engine Shutoff Solenoid Malfunction

If the engine starts, there is no harm in driving the car with this code; but the car may not start again until the engine is repaired.

P0216

Injection Timing Control Circuit Malfunction

The engine may or may not run with this code present. If the engine runs ok, it is safe to drive it to safety.

P0217

Engine Over Temperature Condition

Never drive a car that is overheating. It is possible for this code to be caused by a sensor or wiring failure, but please do not drive the vehicle unless you are sure it is not overheating.

P0218

Transmission Over Temperature Condition

Never drive a car with this code, unless you are sure the transmission is not overheating.

P0219

Engine Over Speed Condition

This code indicates the engine is overrevving. If you are shifting the transmission properly, this code should never arise.

P0220

Throttle/Pedal Position Sensor/Switch "B" Circuit Malfunction

It is generally not safe to drive with these malfunctions. If the computer is confused about the pedal position, it may cause sudden acceleration. If it is only the throttle position sensor that is malfunctioning, the car may be safe to drive, but may not drive properly. Drive only with extreme caution.

P0221

Throttle/Pedal Position Sensor/Switch "B" Circuit Range/Performance Problem

P0222

Throttle/Pedal Position Sensor/Switch "B" Circuit Low Input

P0223

Throttle/Pedal Position Sensor/Switch "B" Circuit High Input

P0224

Throttle/Pedal Position Sensor/Switch "B" Circuit Intermittent

P0225

Throttle/Pedal Position Sensor/Switch "C" Circuit Malfunction

P0226

Throttle/Pedal Position Sensor/Switch "C" Circuit Range/Performance Problem

P0227

Throttle/Pedal Position Sensor/Switch "C" Circuit Low Input

P0228

Throttle/Pedal Position Sensor/Switch "C" Circuit High Input

P0229

Throttle/Pedal Position Sensor/Switch "C" Circuit Intermittent

P0230

Fuel Pump Primary Circuit Malfunction

Fuel pump codes are not harmful to the engine, but they may leave you stranded. The the engine runs, drive with these codes only if necessary to reach safety.

P0231

Fuel Pump Secondary Circuit Low

P0232

Fuel Pump Secondary Circuit High

P0233

Fuel Pump Secondary Circuit Intermittent

P0234

Engine Over Boost Condition

This code indicates a turbo or supercharger overpressure. This can damage the engine. Do not drive with this code present.

P0261

Cylinder #1 Injector Circuit Low

Injector malfunctions will usually cause the engine to miss. A miss caused by these codes is not likely to harm the vehicle, but it may be difficult to drive, depending on the size of the engine. Similarly, contribution faults indicate a cylinder is not firing properly. If the engine runs ok or only misses a little, it is ok to drive it to safety.

P0262

Cylinder #1 Injector Circuit High

P0263

Cylinder #1 Contribution/Balance Fault

P0264

Cylinder #2 Injector Circuit Low

P0265

Cylinder #2 Injector Circuit High

P0266

Cylinder #2 Contribution/Balance Fault

P0267

Cylinder #3 Injector Circuit Low

P0268

Cylinder #3 Injector Circuit High

P0269

Cylinder #3 Contribution/Balance Fault

P0270

Cylinder #4 Injector Circuit Low

P0271

Cylinder #4 Injector Circuit High

P0272

Cylinder #4 Contribution/Balance Fault

P0273

Cylinder #5 Injector Circuit Low

P0274

Cylinder #5 Injector Circuit High

P0275

Cylinder #5 Contribution/Balance Fault

P0276

Cylinder #6 Injector Circuit Low

P0277

Cylinder #6 Injector Circuit High

P0278

Cylinder #6 Contribution/Balance Fault

P0279

Cylinder #7 Injector Circuit Low

P0280

Cylinder #7 Injector Circuit High

P0281

Cylinder #7 Contribution/Balance Fault

P0282

Cylinder #8 Injector Circuit Low

P0283

Cylinder #8 Injector Circuit High

P0284

Cylinder #8 Contribution/Balance Fault

P0285

Cylinder #9 Injector Circuit Low

P0286

Cylinder #9 Injector Circuit High

P0287

Cylinder #9 Contribution/Balance Fault

P0288

Cylinder #10 Injector Circuit Low

P0289

Cylinder #10 Injector Circuit High

P0290

Cylinder #10 Contribution/Balance Fault

P0291

Cylinder #11 Injector Circuit Low

P0292

Cylinder #11 Injector Circuit High

P0293

Cylinder #11 Contribution/Balance Fault

P0294

Cylinder #12 Injector Circuit Low

P0295

Cylinder #12Injector Circuit High

P0296

Cylinder #1 Contribution/Balance Fault

P0300

Random/Multiple Cylinder Misfire Detected

Ignition misfires can damage the catalytic converter, but it is safe to drive a misfiring engine for short distances to reach safety.

P0301

Cylinder #1 — Misfire Detected

P0302

Cylinder #2 — Misfire Detected

P0303

Cylinder #3 — Misfire Detected

P0304

Cylinder #4 — Misfire Detected

P0305

Cylinder #5 — Misfire Detected

P0306

Cylinder #6 — Misfire Detected

P0307

Cylinder #7 — Misfire Detected

P0308

Cylinder #8 — Misfire Detected

P0320

Ignition/Distributor Engine Speed Input Circuit Malfunction

Most engines will not start or run when these malfunctions are present. If your car is running with these codes, it will not harm the engine to drive to safety; but the engine could stop at any time.

P0321

Ignition/Distributor Engine Speed Input Circuit Range/Performance

P0322

Ignition/Distributor Engine Speed Input Circuit No Signal

P0323

Ignition/Distributor Engine Speed Input Circuit Intermittent

P0325

Knock Sensor #1 — Circuit Malfunction (Bank #1 or Single Sensor)

Most engines will run with these codes, but the computer may set limp mode and retard the ignition timing. It is safe to drive with these codes as long as the engine is not knocking. If the engine is knocking, you may reduce the knock by reducing pedal pressure. A severe knock will eventually damage the pistons.

P0326

Knock Sensor #1 — Circuit Range/Performance (Bank #1 or Single Sensor)

P0327

Knock Sensor #1 — Circuit Low Input (Bank #1 or Single Sensor)

P0328

Knock Sensor #1 — Circuit High Input (Bank #1 or Single Sensor)

P0329

Knock Sensor #1 — Circuit Input Intermittent (Bank #1 or Single Sensor)

P0330

Knock Sensor #2 — Circuit Malfunction (Bank #2)

P0331

Knock Sensor #2 — Circuit Range/Performance (Bank #2)

P0332

Knock Sensor #2 — Circuit Low Input (Bank #2)

P0333

Knock Sensor #2 — Circuit High Input (Bank #2)

P0334

Knock Sensor #2 — Circuit Input Intermittent (Bank #2)

P0335

Crankshaft Position Sensor "A" Circuit Malfunction

Most engines will not start or run when these malfunctions are present. If your car is running with these codes, it will not harm the engine to drive to safety; but the engine could stop at any time.

P0336

Crankshaft Position Sensor "A" Circuit Range/Performance

P0337

Crankshaft Position Sensor "A" Circuit Low Input

P0338

Crankshaft Position Sensor "A" Circuit High Input

P0339

Crankshaft Position Sensor "A" Circuit Intermittent

P0340

Camshaft Position Sensor Circuit Malfunction

Engine behavior under these malfunctions is difficult to predict. The engine may or may not run, but it could be damaged if it is run with a camshaft out of position. I do not recommend running the engine with these codes present.

P0341

Camshaft Position Sensor Circuit Range/Performance

P0342

Camshaft Position Sensor Circuit Low Input

P0343

Camshaft Position Sensor Circuit High Input

P0344

Camshaft Position Sensor Circuit Intermittent

P0350

Ignition Coil Primary/Secondary Circuit Malfunction

Depending on the number of coils your engine uses, it may or may not run with these malfunctions. If it runs, it may miss or run rough. A missing engine can damage the catalytic converter; however, this will not occur if you drive only a few miles to safety.

P0351

Ignition Coil "A" Primary/Secondary Circuit Malfunction

P0352

Ignition Coil "B" Primary/Secondary Circuit Malfunction

P0353

Ignition Coil "C" Primary/Secondary Circuit Malfunction

P0354

Ignition Coil "D" Primary/Secondary Circuit Malfunction

P0355

Ignition Coil "E" Primary/Secondary Circuit Malfunction

P0356

Ignition Coil "F" Primary/Secondary Circuit Malfunction

P0357

Ignition Coil "G" Primary/Secondary Circuit Malfunction

P0358

Ignition Coil "H" Primary/Secondary Circuit Malfunction

P0359

Ignition Coil "I" Primary/Secondary Circuit Malfunction

P0360

Ignition Coil "J" Primary/Secondary Circuit Malfunction

P0361

Ignition Coil "K" Primary/Secondary Circuit Malfunction

P0362

Ignition Coil "L" Primary/Secondary Circuit Malfunction

P0370

Timing Reference High Resolution Signal "A" Malfunction

Most engines will not start or run when these malfunctions are present. If your car is running with these codes, it will not harm the engine to drive to safety; but the engine could quit at any time.

P0371

Timing Reference High Resolution Signal "A" Too Many Pulses

P0372

Timing Reference High Resolution Signal "A" Too Few Pulses

P0373

Timing Reference High Resolution Signal "A" Intermittent/Erratic Pulses

P0374

Timing Reference High Resolution Signal "A" No Pulses

P0375

Timing Reference High Resolution Signal "B" Malfunction

P0376

Timing Reference High Resolution Signal "B" Too Many Pulses

P0377

Timing Reference High Resolution Signal "B" Too Few Pulses

P0378

Timing Reference High Resolution Signal "B" Intermittent/Erratic Pulses

P0379

Timing Reference High Resolution Signal "B" No Pulses

P0380

Glow Plug/Heater Circuit "A" Malfunction

Glow plugs are used in diesel engines to ensure ignition. Vehicles with these malfunctions may not start. If the engine starts, it is safe to drive the vehicle to safety.

P0381

Glow Plug/Heater Indicator Circuit Malfunction

P0382

Glow Plug/Heater Circuit "B" Malfunction

P0385

Crankshaft Position Sensor "B" Circuit Malfunction

Most engines will not start or run when these malfunctions are present. If your car is running with these codes and shifting ok, it will not harm the engine to drive to safety; but the engine could quit at any time.

P0386

Crankshaft Position Sensor "B" Circuit Range/Performance

P0387

Crankshaft Position Sensor "B" Circuit Low Input

P0388

Crankshaft Position Sensor "B" Circuit High Input

P0389

Crankshaft Position Sensor "B" Circuit Intermittent

P0400

Exhaust Gas Recirculation Flow Malfunction

Most cars will run with these codes present. If the engine runs, it is safe to drive.

P0401

Exhaust Gas Recirculation Flow Insufficient Detected

P0402

Exhaust Gas Recirculation Flow Excessive Detected

P0403

Exhaust Gas Recirculation Circuit Malfunction

P0404

Exhaust Gas Recirculation Circuit Range/Performance

P0405

Exhaust Gas Recirculation Sensor "A" Circuit Low

P0406

Exhaust Gas Recirculation Sensor "A" Circuit High

P0407

Exhaust Gas Recirculation Sensor "B" Circuit Low

P0408

Exhaust Gas Recirculation Sensor "B" Circuit High

P0410

Secondary Air Injection System Malfunction

P0411

Secondary Air Injection System Incorrect Flow Detected

P0412

Secondary Air Injection System Switching Valve "A" Circuit Malfunction

P0413

Secondary Air Injection System Switching Valve "A" Circuit Open

P0414

Secondary Air Injection System Switching Valve "A" Circuit Shorted

P0415

Secondary Air Injection System Switching Valve "B" Circuit Malfunction

P0416

Secondary Air Injection System Switching Valve "B" Circuit Open

P0417

Secondary Air Injection System Switching Valve "B" Circuit Shorted

P0418

Secondary Air Injection System Relay "A" Circuit Malfunction

P0419

Secondary Air Injection System Relay "B" Circuit Malfunction

P0420

Catalyst System Efficiency Below Threshold (Bank #1)

These codes generally indicate that your catalytic converter is worn out. It is safe to drive with a worn out converter, but the vehicle will not pass a smog inspection (if required by your state).

P0421

Warm Up Catalyst Efficiency Below Threshold (Bank #1)

P0422

Main Catalyst Efficiency Below Threshold (Bank #1)

P0423

Heated Catalyst Efficiency Below Threshold (Bank #1)

P0424

Heated Catalyst Temperature Below Threshold (Bank #1)

P0430

Catalyst System Efficiency Below Threshold (Bank #2)

P0431

Warm Up Catalyst Efficiency Below Threshold (Bank #2)

P0432

Main Catalyst Efficiency Below Threshold (Bank #2)

P0433

Heated Catalyst Efficiency Below Threshold (Bank #2)

P0434

Heated Catalyst Temperature Below Threshold (Bank #2)

P0440

Evaporative Emission Control System Malfunction

Most vehicles will run and are safe to drive with these codes present. If the purge valve is stuck open, the car may not start.

P0441

Evaporative Emission Control System Incorrect Purge Flow

P0442

Evaporative Emission Control System Leak Detected (Small Leak)

P0443

Evaporative Emission Control System Purge Control Valve Circuit Malfunction

P0444

Evaporative Emission Control System Purge Control Valve Circuit Open

P0445

Evaporative Emission Control System Purge Control Valve Circuit Shorted

P0446

Evaporative Emission Control System Vent Control Circuit Malfunction

Vehicles will almost always run and are safe to drive with these codes present. Always check to make sure your fuel cap is present and tight when you have one of these codes (P0455 is most common).

P0447

Evaporative Emission Control System Vent Control Circuit Open

P0448

Evaporative Emission Control System Vent Control Circuit Shorted

P0449

Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction

P0450

Evaporative Emission Control System Pressure Sensor Malfunction

P0451

Evaporative Emission Control System Pressure Sensor Range/Performance

P0452

Evaporative Emission Control System Pressure Sensor Low Input

P0453

Evaporative Emission Control System Pressure Sensor High Input

P0454

Evaporative Emission Control System Pressure Sensor Intermittent

P0455

Evaporative Emission Control System Leak Detected (Gross Leak)

P0460

Fuel Level Sensor Circuit Malfunction

Most cars will run with these codes present; however, check to make sure you don’t have a large fuel leak under the vehicle. Your fuel gage may also be erratic. The car is safe to drive with these codes present, as long as there is not a fuel leak.

P0461

Fuel Level Sensor Circuit Range/Performance

P0462

Fuel Level Sensor Circuit Low Input

P0463

Fuel Level Sensor Circuit High Input

P0464

Fuel Level Sensor Circuit Intermittent

P0465

Purge Flow Sensor Circuit Malfunction

Most vehicles will run and are safe to drive with these codes present. If the purge valve is stuck open, the car may not start. Most vehicles will run and are safe to drive with these codes present. If the purge valve is stuck open, the car may not start.

P0466

Purge Flow Sensor Circuit Range/Performance

P0467

Purge Flow Sensor Circuit Low Input

P0468

Purge Flow Sensor Circuit High Input

P0469

Purge Flow Sensor Circuit Intermittent

P0470

Exhaust Pressure Sensor Malfunction

Most cars will run with these codes present. If the engine runs, it is safe to drive. Note that turbocharged engines may have reduced boost in the presence of these malfunctions.

P0471

Exhaust Pressure Sensor Range/Performance

P0472

Exhaust Pressure Sensor Low

P0473

Exhaust Pressure Sensor High

P0474

Exhaust Pressure Sensor Intermittent

P0475

Exhaust Pressure Control Valve Malfunction

P0476

Exhaust Pressure Control Valve Range/Performance

P0477

Exhaust Pressure Control Valve Low

P0478

Exhaust Pressure Control Valve High

P0479

Exhaust Pressure Control Valve Intermittent

P0480

Cooling Fan #1 Control Circuit Malfunction

Most cars will run in the presence of these malfunctions; but, if the fan does not run properly, the car may overheat when idling. As long as the engine does not overheat, the car is safe to drive.

P0481

Cooling Fan #2 Control Circuit Malfunction

P0482

Cooling Fan #3 Control Circuit Malfunction

P0483

Cooling Fan Rationality Check Malfunction

P0484

Cooling Fan Circuit Over Current

P0485

Cooling Fan Power/Ground Circuit Malfunction

P0500

Vehicle Speed Sensor Malfunction

Most cars will run in the presence of these malfunctions; but the speedometer may not read properly, and the transmission may not shift properly. The car is safe to drive as long as the transmission shifts OK.

P0501

Vehicle Speed Sensor Range/Performance

P0502

Vehicle Speed Sensor Circuit Low Input

P0503

Vehicle Speed Sensor Intermittent/Erratic/High

P0505

Idle Control System Malfunction

Most cars will run in the presence of these malfunctions; but the engine may not idle properly. If the engine does not idle, you may keep it running with a little pedal pressure; however, do not shift an automatic transmission into gear at high rpm as this can damage the transmission.

P0506

Idle Control System RPM Lower Than Expected

P0507

Idle Control System RPM Higher Than Expected

P0510

Closed Throttle Position Switch Malfunction

It is generally not safe to drive with this malfunction. If the computer is confused about the throttle position, it may cause sudden acceleration. If it is only the throttle position sensor that is malfunctioning, the car may be safe to drive, but may not drive properly. Drive only with extreme caution.

P0520

Engine Oil Pressure Sensor/Switch Circuit Malfunction

An engine without oil pressure can be destroyed within a minute’s time. Do not drive with these malfunctions unless you are sure the engine has oil pressure. This will be indicated by an oil pressure gage that reads in range or by an oil pressure lamp that lights during start but extinguishes after starting.

P0521

Engine Oil Pressure Sensor/Switch Range/Performance

P0522

Engine Oil Pressure Sensor/Switch Low Voltage

P0523

Engine Oil Pressure Sensor/Switch High Voltage

P0530

A/C Refrigerant Pressure Sensor Circuit Malfunction

All cars will run in the presence of these malfunctions, but I recommend you not engage the air conditioner until repairs have been made.

P0531

A/C Refrigerant Pressure Sensor Circuit Range/Performance

P0532

A/C Refrigerant Pressure Sensor Circuit Low Input

P0533

A/C Refrigerant Pressure Sensor Circuit High Input

P0534

A/C Refrigerant Charge Loss

P0550

Power Steering Pressure Sensor Circuit Malfunction

All cars will run in the presence of these codes, but the power steering may not work properly. I do not recommend driving with these malfunctions.

P0551

Power Steering Pressure Sensor Circuit Range/Performance

P0552

Power Steering Pressure Sensor Circuit Low Input

P0553

Power Steering Pressure Sensor Circuit High Input

P0554

Power Steering Pressure Sensor Circuit Intermittent

P0560

System Voltage Malfunction

A vehicle may or may not start in the presence of these malfunctions; however, I do not recommend driving with these codes unless you can verify that the car’s voltage is in range. Proper voltage is indicated by a voltmeter in range or a battery lamp that lights during start and then extinguishes after start.

P0561

System Voltage Unstable

P0562

System Voltage Low

P0563

System Voltage High

P0565

Cruise Control On Signal Malfunction

All cars will run in the presence of these codes; but do not engage the cruise control in the presence of these malfunctions.

P0566

Cruise Control Off Signal Malfunction

P0567

Cruise Control Resume Signal Malfunction

P0568

Cruise Control Set Signal Malfunction

P0569

Cruise Control Coast Signal Malfunction

P0570

Cruise Control Accel Signal Malfunction

P0571

Cruise Control/Brake Switch "A" Circuit Malfunction

P0572

Cruise Control/Brake Switch "A" Circuit Low

P0573

Cruise Control/Brake Switch "A" Circuit High

P0574

Through P0580 Reserved for Cruise Codes

P0600

Serial Communication Link Malfunction

A vehicle may or may not run in the presence of these malfunctions. If the vehicle runs and shifts ok, it is safe to drive a short distance to safety.

P0601

Internal Control Module Memory Check Sum Error

P0602

Control Module Programming Error

P0603

Internal Control Module Keep Alive Memory (KAM) Error

P0604

Internal Control Module Random Access Memory (RAM) Error

P0605

Internal Control Module Read Only Memory (ROM) Error

P0606

PCM Processor Fault

P0608

Control Module VSS Output "A" Malfunction

P0609

Control Module VSS Output "B" Malfunction

P0620

Generator Control Circuit Malfunction

A vehicle may or may not start in the presence of these malfunctions; however, I do not recommend driving with these codes unless you can verify that the car’s voltage is in range. Proper voltage is indicated by a voltmeter in range or a battery lamp that lights during start and then extinguishes after start.

P0621

Generator Lamp "L" Control Circuit Malfunction

P0622

Generator Field "F" Control Circuit Malfunction

P0650

Malfunction Indicator Lamp (MIL) Control Circuit Malfunction

All vehicles will run with this malfunction. If this is the only code present, the vehicle is safe to drive, but be sure to have it repaired as soon as practical. With this malfunction present, you will not know what other malfunctions occur unless you rescan the computer.

P0654

Engine RPM Output Circuit Malfunction

Most engines will not start or run when this malfunction is present. If your car is running with this code and shifting ok, it will not harm the engine to drive to safety; but the engine could quit at any time.

P0655

Engine Hot Lamp Output Control Circuit Malfunction

Most cars can run with this malfunction, as long as the engine does not overheat. If the car runs ok and the engine does not seem hot, it is safe to drive short distances or until you can reach safety. If the engine gets hot, it could be damaged severely. If you drive the engine hot, expect to be stranded and to destroy the engine.

P0656

Fuel Level Output Circuit Malfunction

Most cars will run with this code present, but your fuel gage may not work properly. The car is safe to drive with this code present, but do not trust the reading on the fuel gage.

P0700

Transmission Control System Malfunction

Most car engines will run with these codes present, but the transmission may not shift properly. If the transmission shifts hard or the engine over-speeds, driving may damage the car. Some malfunctions may also cause the transmission to lock into high gear, resulting in an engine stall when stopping the vehicle. In these cases, the car may not restart. If the car runs and shifts ok, it is safe to drive to safety, but it could leave you stranded.

P0701

Transmission Control System Range/Performance

P0702

Transmission Control System Electrical

P0703

Torque Converter/Brake Switch "B" Circuit Malfunction

P0704

Clutch Switch Input Circuit Malfunction

P0705

Transmission Range Sensor Circuit Malfunction (PRNDL Input)

P0706

Transmission Range Sensor Circuit Range/Performance

P0707

Transmission Range Sensor Circuit Low Input

P0708

Transmission Range Sensor Circuit High Input

P0709

Transmission Range Sensor Circuit Intermittent

P0710

Transmission Fluid Temperature Sensor Circuit Malfunction

P0711

Transmission Fluid Temperature Sensor Circuit Range/Performance

P0712

Transmission Fluid Temperature Sensor Circuit Low Input

P0713

Transmission Fluid Temperature Sensor Circuit High Input

P0714

Transmission Fluid Temperature Sensor Circuit Intermittent

P0715

Input/Turbine Speed Sensor Circuit Malfunction

The engine may or may not start when these malfunctions are present. If your car is running with these codes, it will not harm the engine to drive to safety; but the engine could stop at any time.

P0716

Input/Turbine Speed Sensor Circuit Range/Performance

P0717

Input/Turbine Speed Sensor Circuit No Signal

P0718

Input/Turbine Speed Sensor Circuit Intermittent

P0719

Torque Converter/Brake Switch "B" Circuit Low

Most car engines will run with these codes present, but the transmission may not shift properly. If the transmission shifts hard or the engine over-speeds, driving may damage the car. Some malfunctions may also cause the transmission to lock into high gear, resulting in an engine stall when stopping the vehicle. In these cases, the car may not restart. If the car runs and shifts ok, it is safe to drive to safety, but it could leave you stranded.

P0720

Output Speed Sensor Circuit Malfunction

Most cars will run in the presence of these malfunctions; but the speedometer may not read properly, and the transmission may not shift properly. The car is safe to drive as long as the transmission shifts OK.

P0721

Output Speed Sensor Circuit Range/Performance

P0722

Output Speed Sensor Circuit No Signal

P0723

Output Speed Sensor Circuit Intermittent

P0724

Torque Converter/Brake Switch "B" Circuit High

This code indicates your brake lights are not working. It may also cause the transmission to get stuck in high gear, which can cause the engine to stall when stopping. It is very unsafe to drive without brake lights, as following vehicles may not stop in time and hit you. If you can confirm that the brake lights are working, the car may be driven to safety.

P0725

Engine Speed Input Circuit Malfunction

The engine may or may not start when these malfunctions are present. If your car is running with these codes, it will not harm the engine to drive to safety; but the engine could stop at any time.

P0726

Engine Speed Input Circuit Range/Performance

P0727

Engine Speed Input Circuit No Signal

P0728

Engine Speed Input Circuit Intermittent

P0730

Incorrect Gear Ratio

Most car engines will run with these codes present, but the transmission may not shift properly. If the transmission shifts hard or the engine over-speeds, driving may damage the car. Some malfunctions may also cause the transmission to lock into high gear, resulting in an engine stall when stopping the vehicle. In these cases, the car may not restart. If the car runs and shifts ok, it is safe to drive to safety, but it could leave you stranded.

P0731

Gear #1 Incorrect Ratio

P0732

Gear #2 Incorrect Ratio

P0733

Gear #3 Incorrect Ratio

P0734

Gear #4 Incorrect Ratio

P0735

Gear #5 Incorrect Ratio

P0736

Reverse Incorrect Ratio

P0740

Torque Converter Clutch Circuit Malfunction

Most car engines will run with these codes present, but the transmission may not shift properly. The transmission may also lock into high gear, resulting in an engine stall when stopping the vehicle. In these cases, the car may not restart. If the car runs and shifts ok, it is safe to drive to safety, but it could leave you stranded.

P0741

Torque Converter Clutch Circuit Performance or Stuck Off

P0742

Torque Converter Clutch Circuit Stuck On

P0743

Torque Converter Clutch Circuit Electrical

P0744

Torque Converter Clutch Circuit Intermittent

P0745

Pressure Control Solenoid Malfunction

Most car engines will run with these codes present, but the transmission may not shift properly. If the transmission shifts hard or the engine over-speeds, driving may damage the car. Some malfunctions may also cause the transmission to lock into high gear, resulting in an engine stall when stopping the vehicle. In these cases, the car may not restart. If the car runs and shifts ok, it is safe to drive to safety, but it could leave you stranded.

P0746

Pressure Control Solenoid Performance or Stuck Off

P0747

Pressure Control Solenoid Stuck On

P0748

Pressure Control Solenoid Electrical

P0749

Pressure Control Solenoid Intermittent

P0750

Shift Solenoid "A" Malfunction

P0751

Shift Solenoid "A" Performance or Stuck Off

P0752

Shift Solenoid "A" Stuck On

P0753

Shift Solenoid "A" Electrical

P0754

Shift Solenoid "A" Intermittent

P0755

Shift Solenoid "B" Malfunction

P0756

Shift Solenoid "B" Performance or Stuck Off

P0757

Shift Solenoid "B" Stuck On

P0758

Shift Solenoid "B" Electrical

P0759

Shift Solenoid "B" Intermittent

P0760

Shift Solenoid "C" Malfunction

P0761

Shift Solenoid "C" Performance Or Stuck Off

P0762

Shift Solenoid "C" Stuck On

P0763

Shift Solenoid "C" Electrical

P0764

Shift Solenoid "C" Intermittent

P0765

Shift Solenoid "D" Malfunction

P0766

Shift Solenoid "D" Performance Or Stuck Off

P0767

Shift Solenoid "D" Stuck On

P0768

Shift Solenoid "D" Electrical

P0769

Shift Solenoid "D" Intermittent

P0770

Shift Solenoid "E" Malfunction

P0771

Shift Solenoid "E" Performance Or Stuck Off

P0772

Shift Solenoid "E" Stuck On

P0773

Shift Solenoid "E" Electrical

P0774

Shift Solenoid "E" Intermittent

P0780

Shift Malfunction

P0781

1–2 Shift Malfunction

P0782

2–3 Shift Malfunction

P0783

3–4 Shift Malfunction

P0784

4–5 Shift Malfunction

P0785

Shift/Timing Solenoid Malfunction

P0786

Shift/Timing Solenoid Range/Performance

P0787

Shift/Timing Solenoid Low

P0788

Shift/Timing Solenoid High

P0789

Shift/Timing Solenoid Intermittent

P0790

Normal/Performance Switch Circuit Malfunction

P0801

Reverse Inhibit Control Circuit Malfunction

This malfunction may prevent the vehicle from being shifted into reverse. It is safe to drive with this code present, but recognize you may get stranded if you need to back up.

P0803

1–4 Upshift (Skip Shift) Solenoid Control Circuit Malfunction

All vehicles will run in the presence of this malfunction. The upshift solenoid is an option on some manual transmissions. The vehicle is safe to drive with this malfunction.

P0804

1–4 Upshift (Skip Shift) Lamp Control Circuit Malfunction



Return to Jeff's DIY
Some of my past projects
See my profile on fixya.com

See my book on Amazon.com: Can I Do It Myself?

Another book of mine you may be interested in: BYTE YOUR SMALL BUSINESS

Contact: Pleasehelpmejeff@gmail.com