P2120
Throttle/Pedal Position Sensor "C" Circuit
A general electrical fault on the "C" channel of the throttle or pedal position sensor. Drive-by-wire pedals carry two or three redundant tracks; "C" is the third channel.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
Symptoms
- Check engine light on
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
Common causes
Ordered by how often each turns out to be the cause.
- Pedal sensor track C failedCommon
- Signal wire openPossible
Parts involved
- Accelerator Pedal Sensor
- Pedal Sensor Wiring
P2120 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.