Electrical and sensors

P2138 — Accelerator Pedal Position Sensor D/E Voltage Correlation

Severity: medium Drive with care, to a shop

What P2138 means

The accelerator pedal contains two independent position sensors (D and E) whose signals should track each other. The control module constantly compares their voltages. If they differ more than allowed, it can't trust the driver's request and limits throttle opening as a safety measure.

Symptoms

  • Check Engine light on
  • Reduced engine power
  • Limp-home mode
  • Sluggish or delayed throttle response
  • Rough or elevated idle
  • Engine won't rev past a set limit

Possible causes

  1. Failed accelerator pedal position sensor (pedal assembly)
  2. Open, corroded or shorted sensor wiring
  3. Poor connection at the pedal or PCM connector
  4. Problem with the 5 V reference or sensor ground
  5. Misaligned or damaged pedal assembly
  6. Rarely, a faulty PCM or throttle body

How to diagnose

  1. Scan all codes and freeze-frame data, looking for related pedal or throttle codes
  2. Inspect the pedal for play, obstructions, floor mat interference and correct mounting
  3. In live data, press the pedal slowly and compare sensors D and E; they should move smoothly and together
  4. Inspect the pedal connector for corrosion, moisture and bent pins
  5. Measure the 5 V reference, ground and signal wires with a multimeter
  6. Test the harness for opens and shorts, wiggling it while measuring
  7. Check the throttle body and its signals if the pedal tests good
  8. After repair, clear the code and perform a throttle relearn if the manufacturer requires it

Common fixes

  • Replace the accelerator pedal assembly
  • Repair the wiring harness or connector
  • Clean terminals and restore sensor power and ground
  • Reinstall or secure the pedal assembly correctly
  • Replace the throttle body or update PCM software if confirmed as the cause

P2138 on different brands

Ford · manuals
On Ford, P2138:00 (no sub type information) in the 2024-2025 gasoline-engine monitor strategy means APP D/E circuit disagreement; it describes the detected condition, not a confirmed failed part.

Questions and answers

What does code P2138 mean?

Two accelerator pedal position sensors are sending signals that don't agree. The PCM can't be sure where the pedal really is, so it limits engine power.

Can I drive with P2138?

Only briefly and with care until it's repaired. Power is limited and throttle response can be unpredictable.

Do I need a new pedal for P2138?

Often yes, but check the connector, wiring, reference voltage and ground first. Replace the pedal if the wiring is good and the sensor signals still disagree.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.