P2138
Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
Throttle control (drive-by-wire)
Generic OBD-II
High
What it means
P2138 means the two accelerator-pedal position signals (D and E) don't agree with each other. The ECM cross-checks these redundant signals to trust your pedal input, so when they disagree it can't tell how far you're pressing and drops the engine into reduced-power or idle-only mode. It's usually a failing pedal sensor or a wiring/connection fault, and it needs prompt repair.
High
Can I keep driving? Often not — a mismatch between the two pedal signals usually forces reduced-power/idle-only mode where the engine barely responds; repair before depending on the car.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power or 'limp' (failsafe) mode, sometimes idle-only
- Little or no response when pressing the accelerator
- Hesitation or surging
Common causes
Most likely first
- Faulty accelerator pedal position sensor (D and E share one assembly)Likely
- Wiring open, shorted, or chafed between the two sensor circuitsCommon
- Poor connection or corrosion at the pedal sensor connectorCommon
- 5-volt reference or ground fault affecting one of the two signalsLess often
- Failing ECM/PCMLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and record the D and E readings to see which one is off.
- Inspect the accelerator pedal connector and wiring for damage, corrosion, or a poor pin.
- With the key on, confirm a steady 5-volt reference and clean ground for both sensor circuits.
- Watch both signals sweep smoothly and in proportion as the pedal is pressed; a flat or mismatched trace points to the sensor.
- Replace the accelerator pedal position sensor assembly if the two elements don't track; suspect the ECM only after wiring is verified.
FAQ
Quick answers
Is it safe to drive with P2138?+
Not really — this fault usually locks the car into reduced power or idle-only, which is unsafe in traffic. Get it repaired before driving normally.
Can I just clear P2138?+
Clearing it won't help; because two signals disagree, the ECM re-checks constantly and the code returns almost immediately until the sensor or wiring is fixed.
Related codes
Often seen with P2138
Read & clear P2138 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX