01 Automotive Electrical Components: Functions, Troubleshootin… • 02 What is the Purpose of Hazard Lights and How to Use Them Pr… • 03 Understanding the Differences Between SAE and Metric Sockets • 04 U0011 Medium Speed CAN Communication Bus Performance • 05 This Is Why Your Car’s Brake Master Cylinder Is Failing • 06 The RB26DETT Skyline Engine: Unleashing the Best in Perform… • 07 Cruise Control: Understanding Its Functionality and Best Pr… • 08 This Is Why Your Car’s Battery Terminals Are Corroded • 09 What Is Blow-By & How to Prevent It From Harming Your Engine • 10 Should You Admit Fault in a Car Accident if It's Your Fault? •

DTC codes / BMW codes / P1623

P1623 · BMWPedal Position Sensor Potentiometer Supply

P1623 on BMW vehicles indicates that the engine control module (ECM) has detected an out-of-range voltage on the supply circuit feeding the pedal position sensor potentiometer, which is part of the accelerator pedal assembly. The ECM monitors this reference voltage and sets the code when the signal falls outside the expected range, often due to a wiring fault, poor connection, or a failing sensor.

SystemPowertrain
Code typeBMW specific
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • Illumination of the check engine light (CEL) on the dashboard.
  • Reduced engine power or limp mode, limiting acceleration.
  • Hesitation or stumble when pressing the accelerator pedal.
  • Unresponsive or erratic throttle behavior.
  • Often no symptoms besides the warning light, especially in early stages.

Common causes, most likely first

  1. Corroded, loose, or damaged electrical connector at the accelerator pedal sensor.
  2. Chafed or broken wires in the harness between the pedal sensor and the ECM.
  3. Faulty accelerator pedal position sensor (potentiometer) internally shorted or open.
  4. Poor ground connection for the sensor circuit.
  5. ECM software glitch or internal fault (less common).
  6. Water intrusion or contamination in the pedal sensor connector.
  7. Aftermarket accessories improperly wired into the sensor circuit.

How to diagnose and fix it

  1. Perform a visual inspection of the accelerator pedal sensor connector and wiring for damage, corrosion, or loose pins.
  2. Use a diagnostic scan tool to read live data from the accelerator pedal position sensors and compare readings to specifications.
  3. Check the reference voltage supply at the sensor connector with a multimeter; verify it matches the manufacturer's specified range (typically around 5 volts).
  4. Inspect the ground circuit for the sensor and ensure it has low resistance to chassis ground.
  5. If wiring and connections are good, test the sensor's resistance across its range of motion and replace the accelerator pedal assembly if out of spec.
  6. Clear the fault codes and perform a road test to verify the repair; if the code returns, recheck the ECM and harness for intermittent faults.

Before replacing the accelerator pedal assembly

  • A common oversight is failing to check the ground circuit for the pedal sensor; a poor ground can mimic a faulty sensor and lead to unnecessary replacement.
  • The code can be set by a momentary voltage spike or glitch, so always clear the code and test-drive before condemning parts.
  • On some BMW models, the pedal sensor supply is shared with other sensors, so a fault elsewhere can affect the reference voltage and set P1623.
  • Aftermarket floor mats or debris can interfere with pedal movement and cause erratic sensor signals, so check for physical obstructions first.
  • The ECM may set P1623 in conjunction with other throttle-related codes; always diagnose the root cause rather than treating each code separately.

Can I keep driving with P1623?

If the vehicle is in limp mode or the accelerator response is erratic, avoid driving until repaired because reduced power can be a safety hazard. If the only symptom is the warning light and the car drives normally, you can drive cautiously to a repair shop, but do not ignore the code.

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.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage