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DTC codes / BMW codes / P1625

P1625 · BMWPedal Position Sensor Potentiometer Supply Channel 2 Electrical

P1625 on BMW vehicles indicates that the engine control module (ECM) has detected an electrical fault on the supply channel for the second potentiometer inside the accelerator pedal position sensor. The ECM monitors the voltage on this dedicated supply line and sets the code when the signal falls outside the expected range, which can be caused by a wiring issue, a faulty pedal sensor, or an internal ECM problem.

SystemPowertrain
Code typeBMW specific
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • The check engine light or electronic throttle control warning light illuminates on the dashboard.
  • The engine may enter limp mode, limiting power and engine speed to a low threshold.
  • The accelerator pedal may feel unresponsive or exhibit a delayed reaction when pressed.
  • In some cases, the vehicle may stall or hesitate during acceleration.
  • Often no symptoms besides the warning light, especially if the fault is intermittent.

Common causes, most likely first

  1. Wiring harness damage (chafed, corroded, or broken wires) between the accelerator pedal sensor and the ECM.
  2. Faulty accelerator pedal position sensor (potentiometer channel 2 internal failure).
  3. Poor electrical connection at the pedal sensor connector or ECM connector (loose pins, corrosion).
  4. Water intrusion or contamination in the pedal sensor connector or wiring.
  5. Internal ECM driver circuit failure for the sensor supply voltage.
  6. Aftermarket or incorrect pedal sensor installed (wrong part number or incompatible).

How to diagnose and fix it

  1. Perform a visual inspection of the accelerator pedal sensor wiring and connector for damage, corrosion, or loose pins.
  2. Use a diagnostic scan tool to read live data for both pedal position sensor channels and compare their voltages for consistency.
  3. Check the supply voltage (typically 5V reference) at the pedal sensor connector with a multimeter; repair wiring if voltage is missing or out of spec.
  4. Inspect the ECM connector for corrosion or loose terminals, and perform a wiggle test on the harness while monitoring live data.
  5. If wiring and connections are good, replace the accelerator pedal position sensor assembly with a genuine BMW part.
  6. After repair, clear the fault codes and perform a throttle adaptation reset using a BMW-compatible scan tool.
  7. If the code persists after sensor replacement and wiring checks, diagnose the ECM for internal faults.

Common Misdiagnosis Traps for P1625

  • A low or missing reference voltage on channel 2 can be caused by a short to ground in the wiring, which is often overlooked when the sensor itself is replaced.
  • The accelerator pedal sensor on BMW models often has two potentiometers with opposite voltage sweeps; a fault in one channel may not trigger obvious drivability symptoms until the ECM limits power.
  • Water ingress into the connector behind the pedal can cause intermittent faults that only appear in wet conditions, so a dry-weather inspection may miss the root cause.
  • After replacing the pedal sensor, a throttle adaptation reset is required; otherwise, the ECM may continue to set the code due to learned values.
  • This code can also be set by a poor ground connection for the sensor circuit, which is often overlooked when focusing only on the positive supply side.

Can I keep driving with P1625?

If the vehicle is in limp mode, driving is not recommended because power is severely limited and could create a safety hazard. If the warning light is on but the car drives normally, you can drive cautiously to a repair shop, but avoid aggressive acceleration or high speeds until the fault is diagnosed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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