P2138 code meaning
Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
Powertrain system Generic code P21xx codes Check engine light
What P2138 means
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.
P2138 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2138
- Engine warning lamp with reduced engine power message
- Sluggish, capped acceleration
- Traction or stability control may be switched off on some models
Common causes of P2138
- Most likelyWater or corrosion in a pedal or inline harness connector
- Most likelyWorn pedal sensor with one track drifting
- PossiblePoorly crimped or loose terminals raising resistance
- Less likelyAftermarket equipment tapped into pedal or 5 V reference circuits
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Accelerator pedal position sensorPedal sensor wiring
What each part of P2138 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 1 | Area: fuel and air metering. |
| 38 | The exact fault in that area. |
What to do next
- Note P2138 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2138
What does P2138 mean?
P2138 means "Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P2138?
Drive gently and only to a workshop. With P2138 the car can go into limp mode (reduced power) to protect itself.
Will P2138 fail an emissions test?
Yes, it can. P2138 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2138 to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2138 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.