Powertrain, generic (extended)

P2109 Throttle/Pedal Position Sensor A Minimum Stop Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Ice or carbon holding the throttle plate off its rest stop
ECM software with oversensitive detection (update available)
Rest position not relearned after cleaning or replacing the throttle body
Sensor A worn or drifted at the closed end of its track

Symptoms

  • Engine warning lamp, often after a cold or wet night
  • Raised or unsteady idle
  • Reduced power until the fault clears

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–600
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

throttle position sensorthrottle bodyecm

Related codes

P2113P2114P0121P0122P2119P2135

References: static.nhtsa.gov, static.nhtsa.gov, patents.google.com, law.cornell.edu.