DTC P2121: Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance [08/2013 - ]: Fail-Safe

The accelerator pedal sensor assembly has 2 (main and sub) sensor circuits. If a malfunction occurs in either of the sensor circuits, the ECM detects the abnormal signal voltage difference between the 2 sensor circuits and switches to fail-safe mode. In fail-safe mode, the ECM limits the engine output. If both circuits malfunction, the ECM regards the angle of the accelerator pedal as being fully closed. In this case, the throttle valve remains closed as if the engine is idling. If a pass condition is detected and then the ignition switch is turned off, the fail-safe operation stops and the system returns to a normal condition.