DTC P0121: Throttle Position Sensor Circuit - Range/Performance Problem: Condition

DTC is set when difference between actual throttle opening value (detected by Throttle Position (TP) sensor) and throttle opening value calculated by ECM is more then predetermined, with engine at normal operating temperature and correct speed, and without intake manifold pressure variation (constant throttle). Throttle opening is calculated by PCM from engine speed and intake manifold pressure. TP sensor is continuously monitored. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• TP sensor malfunction.
• High resistance in TP sensor circuit.
• ECM malfunction.