Jeff's DIY

Advice on doing your own diagnosis and repair

Advice from the book Can I Do It Myself?

Engine Revs on its Own

If your car has a throttle cable, check the return spring on the throttle body to ensure the throttle closes by the spring. If your throttle is controlled electronically, the problem may be with the accelerator pedal position sensor. That sensor is usually attached to the pedal and should produce a resistance between the ground and signal pins that changes linearly as the sensor input is rotated. You can test it with an ohmmeter. If the engine light is on, the problem may also be in the throttle controller on the throttle body. You can verify that condition by extracting the trouble codes from the computer using a scanner. See more about scanning the computer in the Auto Electrical Basics section of the book.

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