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

DTC is set when Engine Control Module (ECM) detects throttle opening is to small (rationality-low) while engine is operating under high load and high engine speed. DTC is also set when ECM detects throttle opening is to large (rationality-high) while engine is operating under low load and low engine speed. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• ECM malfunction.
• Intake air system malfunction.
• Mass Air Flow (MAF) sensor malfunction.
• Throttle Position (TP) sensor malfunction.
• TP sensor circuit malfunction.