What P2138 means
The two sensors in your gas pedal disagree about how far it's pressed. The computer can't trust the pedal, so it puts the car into reduced-power mode. A worn pedal assembly or corroded connector is the usual cause.
How the engine computer detects it
The two redundant accelerator pedal position sensors disagree by more than the allowed tolerance. The ECU cannot trust either signal and switches to limp-home with very limited torque. Often appears intermittently with a worn pedal sensor before failing outright.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
Common causes
- Pedal position sensor worn or contaminated Most likely
- Corroded pedal connector Possible
How to diagnose P2138
- Check the connector on the gas pedal assembly for corrosion or loose pins.
- With a scanner, watch both pedal position signals while slowly pressing the pedal. They should rise smoothly and stay in proportion.
- If a signal drops out or jumps, replace the pedal assembly. The sensor is part of it.
- Check for service bulletins: some vehicles need a software update together with the new pedal.
Vehicles that report P2138 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Subaru Outback | 2005–2007 | 77 | 118k | |
| Chevrolet Malibu | 2010–2018 | 53 | 62k | |
| Subaru Legacy | 2004–2006 | 19 | 96k | |
| Chevrolet Impala | 2006–2012 | 19 | 54k | |
| Chevrolet Silverado 1500 | 2007–2018 | 11 | — | |
| Chevrolet Sonic | 2012–2014 | 6 | — | |
| Buick Lacrosse | 2006–2010 | 5 | 71k | |
| Chevrolet Traverse | 2012–2016 | 5 | 60k | |
| Subaru Forester | 2005–2015 | 5 | 81k | |
| GMC Acadia | 2012–2021 | 5 | — |
Counts of owner complaints to the NHTSA that mention P2138 (290 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 2
- Generic (SAE) code
- 138
- Specific fault
Questions drivers ask
Can I drive with code P2138?
Carefully, and only to a safe place or a shop. The car may barely accelerate, which can be dangerous in traffic.
Will my car pass an emissions inspection with P2138?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P2138 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P2138 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P2138. They can point to a shared cause, so it's worth checking them together.
- P2122Throttle/Pedal Position Sensor "D" Circuit Low14 complaints
- P2127Throttle/Pedal Position Sensor "E" Circuit Low10 complaints
- P1125Manufacturer-specific code5 complaints
- C0242PCM Indicated ABS Malfunction4 complaints
- P2106Throttle Actuator Control System — Forced Limited Power4 complaints
- P2128Throttle/Pedal Position Sensor "E" Circuit High4 complaints
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.