P2138: Throttle or pedal position sensors D and E voltage mismatch
The two accelerator pedal position signals (D and E) do not agree with each other as they should. Usually the connector, a wire or the sensor.
| Code | P2138 |
|---|---|
| System | Engine and transmission |
| Group | P21xx, Throttle, injection and emissions |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P2138 means
For safety, the position on the accelerator pedal is measured by two sensors at once, and the ECU checks that their signals say the same thing. This code means sensors D and E disagree, so the ECU cannot tell which to believe and cuts power. On most cars sensors D and E are the pedal ones.
Most common causes
- Dirty, loose or corroded accelerator pedal connector
- A poor contact on one sensor wire or a faulty shared ground
- A worn pedal sensor (usually the whole pedal unit is replaced)
- A floor mat rubbing on the pedal
- A fault in the engine ECU, which is uncommon
Symptoms
- Engine or throttle warning light on
- Reduced power or limp mode
- Odd or jerky throttle response
- High or unstable idle
Can you drive with P2138?
With care You can usually drive with care and reduced power. See a garage soon, as the car may drop to idle without warning.
Open the bonnetthe in-depth explanation
How to check it
Use a live data reader to watch both pedal signals while slowly pressing the pedal to the floor: they should move together. If one drifts away or jumps at some point, the pedal or its connector is the suspect.
How to read and clear P2138 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P2138 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P2134 Circuit F of the throttle or pedal position sensor or switch fails
- P2135 Throttle or pedal position sensors A and B voltage mismatch
- P2136 The throttle or pedal position sensor signals do not match each other
- P2137 Voltages B and C of the throttle or pedal position sensor or switch disagree
- P2139 Voltages D and F of the throttle or pedal position sensor or switch disagree
- P213A The EGR throttle B circuit is open
- P213B The exhaust gas recirculation throttle control circuit B gives readings outside
- P213C The exhaust gas recirculation throttle control circuit B gives a lower signal
- P2100 Throttle actuator A control motor circuit open
- P2101 Throttle actuator A control motor circuit range or performance
- P2102 Throttle actuator A control motor circuit low
- P2104 Throttle control system: forced idle
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: Accelerator.
What does code P2138 mean?
For safety, the position on the accelerator pedal is measured by two sensors at once, and the ECU checks that their signals say the same thing. This code means sensors D and E disagree, so the ECU cannot tell which to believe and cuts power. On most cars sensors D and E are the pedal ones.
Can you drive with P2138?
You can usually drive with care and reduced power. See a garage soon, as the car may drop to idle without warning.
How do you clear P2138?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P2138 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
