This is a 2007 Mistubishi Lancer ES with a P2138 code.

I have replaced the pedal sensor and a complete new throttle body and after clearing the code my engine light eventually comes back on and I have no acceleration. But after turning the car off and waiting for a few minutes, I can start the car and have acceleration with check engine light on. Then I clear the engine light with a OBD-II diagnostic reader and there is a humming noise coming from throttle body.


The accelerator position sensor connects to the ECU (Engine Control Unit) or a PCU (Powertrain Control Unit), not the throttle body, so replacing the throttle body isn't going to help. If you've replaced the sensor and you still get the problem then there's a problem with the wiring between the sensor and the ECU or the ECU is faulty.

First check the connector which plugs into the sensor, make sure it's clean and all the pins are seated properly. Then trace the wiring to the ECU and check to make sure there aren't exposed wires or some obvious fault. If there's no visible issues then if could be the ECU, for that you'd probably need to go to a specialist for some diagnostics. I don't know if ECU replacement is a home job in that model, sometimes they need to be programmed for your specific vehicle. It's also an expensive way to go if that turns out not to be the problem!

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