P2109
Throttle/Pedal Position Sensor A Minimum Stop Performance
The ECU detects that the throttle position sensor A signal at the closed-throttle stop does not match the learned minimum value. The mechanical or electrical zero reference of the throttle has drifted out of the expected range, often after cleaning, replacement or wear.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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.
- Carbon deposits on throttle plateCommon
- Throttle position sensor driftCommon
- Idle/throttle relearn not performedPossible
Parts involved
- Throttle Position Sensor
- Throttle Body
- Throttle Actuator
P2109 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.