What is the cause of reduced engine power usually causes ?

Usually a code is set for the TAC system......this system uses data from your accel pedal, to control the opening of the motorized throttle plate......it does not use a cable to physically move the throttle plate...

More often than not, the problems I have seen, are wire connections to the harness at the throttle body, causing intermittent conditions...

Did you check the grounds behind both heads?

I check all grounds seem ok

The throttle connector is lose .. I used some tape to make it not moving


The code p2138 APP SENSOR .. I opened the app sensor and retighting again

Really tough to diagnose this system without a Tech II scan tool....

Your accelerator pedal position sensor set the code.......it could be the sensor, or the wiring between the ECM and the sensor.....

Basically, the app sends a signal to the ECM......based on that, the ECM commands the motor on the throttle plate to open/close.....there are two throttle position sensors reporting back to the ECM, telling it what the position of the throttle plate is....

I have no idea what that means......to diagnose the app sensor, all you can do is check the connections to it....a scan tool is needed to see if there is a "blip" in data, as you slowly depress and release the gas pedal.....

Like I said, without a scan tool, and trouble tree, you are only guessing what the problem is, unless you can visually see the problem....

Like I said before, when it comes to this system, I have seen many throttle bodies needlessly replaced, when the only problem was a loose female connector in the harness, or a broken wire INSIDE THE HARNESS, causing intermittent conditions....

In your case it is kind of narrowed down to the APP sensor circuit......