P2138 Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation

P2138 means the two accelerator-pedal position signals (D and E) that should move together no longer correlate. The system uses redundant pedal sensors for safety, so a mismatch forces a fault and often a reduced-power mode.

Code details

Generic OBD-II · P2

System: Speed / Idle
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the pedal assembly before checking the connector and grounds, since wiring faults commonly cause correlation codes.

Symptoms of P2138

Reduced-power / limp mode.
Dead or erratic throttle response.
A warning light on the dash.

Common causes of P2138

A failing accelerator-pedal position sensor.
Corroded or spread connector pins.
Wiring, ground, or reference faults.
Moisture intrusion at the pedal connector.

Useful checks before replacing parts

Compare the D and E pedal voltages live across the full sweep.
Inspect the pedal connector and wiring for corrosion or spread terminals.
Check for a shared ground or reference fault affecting both signals.

Related OBD-II codes

These nearby speed / idle entries can help compare wording and pin down the fault area.