DTC P0121: Throttle Position (TP) Sensor Circuit Performance Problem: Condition

DTC is set when ECM (PCM) detects throttle opening is to small with vehicle operating under high load and high engine speed. DTC is also set when ECM (PCM) detects throttle opening is to large with vehicle operating under low load and low engine speed. MIL is illuminated when ECM (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• Intake air system malfunction.
• TP sensor malfunction.
• ECM (PCM) malfunction.