P0123
Throttle/Pedal Position Sensor "A" High Input
The TPS signal voltage exceeds the upper acceptable threshold. As with P0122, limp-home mode is typical until the fault clears.
- 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.
- Signal wire shorted to supply voltageCommon
- Sensor ground brokenPossible
- TPS internally failedLess likely
Parts involved
- Throttle Position Sensor
- Throttle Position Sensor Wiring
P0123 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.