What it means
The D and E throttle or pedal position signals do not agree within the allowed range. The code identifies a correlation fault; the vehicle’s response depends on its design.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Position channels D and E provide redundant position information, commonly from the accelerator pedal, though their assignment depends on the vehicle. P2138 sets when the control module sees that D and E no longer maintain their expected relationship, which can result from a worn or contaminated sensor or a poor pedal connector.
Common causes
Most likely first.
- Pedal position sensor worn or contaminated
- Corroded pedal connector
Symptoms
- Check engine light on
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
How to diagnose it
- Record freeze-frame data and graph D and E live data while slowly pressing and releasing the accelerator; note whether either signal jumps or the relationship changes unexpectedly.
- Inspect the pedal sensor connector and harness for corrosion, contamination, loose or pushed-back pins, and damage near the pedal movement area.
- Check sensor power, ground, and the D and E signal circuits against the wiring diagram and manufacturer's specification.
- Compare both signals through the full pedal travel and, if accessible in scan data, compare them with the module's reported pedal position or requested throttle.
- If wiring and connector checks pass, test the pedal position sensor assembly using the manufacturer's procedure.
Common fixes
- Clean and secure corroded or contaminated pedal connector terminals.
- Repair damaged pedal harness wiring or poor power, ground, or signal connections.
- Replace the pedal position sensor or pedal assembly if D/E tracking fails the manufacturer's test.
- Repair a verified control-module fault only after the pedal sensor circuits have passed testing.
Can I keep driving?
Avoid driving if the accelerator response is limited, delayed, or unpredictable; the vehicle may restrict power or enter limp mode. If pedal response is normal, limit driving until checked, as a worsening D/E mismatch can leave you unable to accelerate reliably.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.