P2121
Throttle/Pedal Position Sensor "C" Range/Performance
The "C" channel of the throttle or pedal sensor produces an electrically valid signal that does not match the other channels or the operating point.
- 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.
- Sensor track C wornCommon
- Correlation with tracks A/B lostPossible
- Sensor element aged beyond calibration windowLess likely
Parts involved
- Accelerator Pedal Sensor
P2121 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.