P2138 2008 Pontiac Grand Prix GXP

Question

I have a 2008 Pontiac Grand Prix GXP with the 5.3 liter V*, my ACC sensor was faulting out per Autozone's code reader so I bought their aftermarket replacement. 4 days later my check engine light came back on. I took it back to them to read the codes and they pulled a P2122 Throttle/Pedal Position Sensor/Switch "D" Circuit Low Input and P2238 Accelorator Pedal Position Sensor1-2 Corrolation Error. My question is this...Do I need to have the dealer calibrate the pedal and throttle body or what else could cause these errors. The car runs good, it is not going into limp mode like it was before I replaced the Accelorator Pedal. However I can see the gas milage dropping slightly, so far just from an average of 19.5 to 19.1. Any help would be appreciated. Thanks.

Answer 1

P2138 Accelerator pedal position (APP) sensor 1-2 correlation

P2122 Accelerator pedal positon (APP) circuit low

You probably will not need any of the  APP sensor , and no dealer does not have to calibrate  a aftermarket scan tool that has the factory protocals can reset it. When you have a P2122 this is circuit low, this is what is causing P2138, Historically you have had a a/c pressure switch problem. the a/c pressure switch has a 5 volts reference which is also shared by the APP sensor , Here in this diagram you can see the 5 volts reffernce from the a/c pressure switch then it is shared with the APP sensor , If the a/c pressure sensor still gives a short or the connection is shorted, this will cause both code condition, try this  disconnect the a/c pressure sensor clear the code if P2138 and P2122 does not code up, replace the a/c pressure switch ,