P2C99
Throttle Actuator A Control Exceeded Learning Limit
The required adaptation offset for throttle actuator A exceeds the calibrated learning window. Mechanical wear, deposit build-up, or sensor drift beyond compensation.
- 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.
- Deposits on throttle plate or boreCommon
- TPS reference driftedPossible
Parts involved
- Throttle Actuator A
- Throttle Position Sensor
- ECM
P2C99 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.