The throttle position (TP) sensor is a potentiometer that varies resistance according to changes in throttle plate position. The PCM measures the signal voltage from the TP sensor, which is a reduced value of the PCM 5 volt reference. The voltage ranges from 0.15-0.55 volts at 0 percent throttle position to 4.65 volts at wide open throttle. DTC P0122 sets when the TP sensor signal voltage at the PCM is below the calibrated voltage value.

DTC P0122 will set if TP sensor voltage is less than 0.1 volts when:

DTC P0122 diagnostic runs continuously with engine running.

P0122 is a type B DTC.

If DTC P0452 and P0530 are also set, a short to ground on the 5 volt reference circuit may exist. Refer to 5 Volt Reference Circuit Error Diagnosis.

To locate an intermittent problem, use the scan tool to monitor the TP sensor voltage with the ignition ON and the engine OFF. Wiggling the wires while watching for a change in TP sensor voltage may locate the area where an open or short to ground in the wiring could lie.

Important: The A/C pressure sensor, fuel tank pressure sensor, and TP sensor are all tied to the same 5 volt reference source.

An intermittent open in the TP sensor can cause this DTC to set. Use the scan tool to monitor the TP sensor as the accelerator pedal is slowly depressed. The voltage should change smoothly from 0.35 volts at 0 percent throttle, to 4.65 volts at wide open throttle, 0.15-0.55 volts.