DTC P2121: Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance [09/2014 - 08/2016]: Fail-Safe

When DTC P2120, P2121, P2122, P2123, P2125, P2127, P2128 or P2138 is stored, the ECM enters fail-safe mode. If 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. As a result, the throttle valve is closed and the engine idles.

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.