P2109Throttle/Pedal Position Sensor A Minimum Stop Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2109 flags an implausible rest reading on position signal A: with the throttle or pedal resting on its lower mechanical stop, the minimum learned at key-on falls outside the window the calibration accepts. Ford names its first throttle body sensor TP A, so on such layouts the code concerns the throttle. Subaru documents P2109: bulletin 09-102-23 traces it on the 2022 WRX to a throttle plate that has frozen shut and supplies new ECM software, and 09-97-22 adds improved detection logic for 2020-2022 Legacy and Outback. A Delphi patent describes several learn attempts before an obstruction is reported. Circuit faults on A have their own codes (P0120-P0123); P2113-P2117 run the same check for letters B to F. Expect a warning lamp and possibly limp mode.
- What you may notice
- Engine warning lamp, often after a cold or wet night
- Raised or unsteady idle
- Reduced power until the fault clears
- Likely causes
- LikelyIce or carbon holding the throttle plate off its rest stop
- PossibleECM software with oversensitive detection (update available)
- PossibleRest position not relearned after cleaning or replacing the throttle body
- RareSensor A worn or drifted at the closed end of its track
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.