Circuit Faults

UNSTABLE IDLE
A broken or loose Throttle Position (TP) sensor can cause intermittent bursts of fuel from the injector and cause an unstable idle, because the Powertrain Control Module (PCM) detects the throttle is moving.

TP SENSOR CIRCUIT FAULTS
Open Circuit
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. Refer to Code 22 Throttle Position Sensor Circuit (Signal Voltage Low). Powertrain Controls - ECM/PCM

Short Circuit
If the TP sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will be set. Refer to Code 21 Throttle Position Sensor (Signal Voltage High). Powertrain Controls - ECM/PCM

Circuit Problems
A problem in any of the TP sensor circuits will set either of the codes listed above.