DTC P2121: Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance [06/2014 - 10/2017]: Fail-Safe

The accelerator pedal position sensor has 2 (main and sub) sensor circuits. The ECM detects the abnormal signal voltage difference between the 2 sensor circuits and switches to fail-safe mode. If the either of the 2 sensor circuits malfunctions, the ECM limits the engine output. If both of the circuits malfunction, the ECM regards the accelerator pedal as being released. In this case, the throttle valve remains closed as if the engine is idling.

If a pass condition is detected and then the engine switch is turned off, the fail-safe operation stops and the system returns to normal.