P2138Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2138 is the standard plausibility check of a two-track accelerator pedal: D and E are pedal sensors 1 and 2 at GM, Ford and VW. GM's 2007 tables set it when the tracks differ by more than 10 % or their learned rest values by over 5 % (Type A); the 2023 table uses 0.12-0.18 V for 0.25 s in one trip. Ford flags more than 0.9 degrees and since 2020 lights MIL and wrench lamp; the 2014 VW Passat allows 0.17-0.70 V. GM bulletin 07-06-04-019F blames water entering the instrument panel to body harness connector, and special coverage N182188250 covers a pedal sensor connection on the Malibu (2016-2018), LaCrosse (2017-2018) and Regal (2018). Single-track faults have their own codes (P2122-P2128). The ECU reduces power.
- What you may notice
- Engine warning lamp with reduced engine power message
- Sluggish, capped acceleration
- Traction or stability control may be switched off on some models
- Likely causes
- LikelyWater or corrosion in a pedal or inline harness connector
- LikelyWorn pedal sensor with one track drifting
- PossiblePoorly crimped or loose terminals raising resistance
- RareAftermarket equipment tapped into pedal or 5 V reference circuits
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.