P2621
Throttle Position Output Circuit Low
The buffered throttle position output that the engine controller sends to the transmission and body modules is below the expected level. Usually a short to ground or a failed output stage.
- Check engine light: Yes
- Emissions related: No
- 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.
- Output wire shorted to groundCommon
- Output buffer transistor failedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Control Module
- Signal Output Buffer
- Wiring Harness
P2621 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.