Faulty accelerator pedal position sensor (worn tracks or internal failure).; Corroded or damaged electrical connector at the pedal sensor.; Wiring harness damage (open, short, or chafed wires) between the pedal sensor and the ECM.; Poor electrical ground connection for the sensor circuit.; ECM software issue or internal fault (less common).; Aftermarket or incorrect pedal assembly installed.

DTC codes / BMW codes / P1543

P1543 · BMWPedal Position Sensor

Q: What does code P1543 mean?

Pedal Position Sensor. P1543 on BMW vehicles indicates that the engine control module (ECM) has detected an implausible or missing signal from the pedal position sensor, which is part of the accelerator pedal assembly. The ECM compares the two redundant sensor signals and sets this code when they do not correlate or when the voltage falls outside the expected range, often triggering reduced engine power.

P1543 on BMW vehicles indicates that the engine control module (ECM) has detected an implausible or missing signal from the pedal position sensor, which is part of the accelerator pedal assembly. The ECM compares the two redundant sensor signals and sets this code when they do not correlate or when the voltage falls outside the expected range, often triggering reduced engine power.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the check engine light and possibly the electronic throttle control (ETC) warning light.
Reduced engine power or limp mode, limiting vehicle speed and acceleration.
Hesitation or stumble when pressing the accelerator pedal.
Unresponsive or delayed throttle response.
Often no symptoms besides the warning light, especially if the fault is intermittent.

Common causes, most likely first

Faulty accelerator pedal position sensor (worn tracks or internal failure).
Corroded or damaged electrical connector at the pedal sensor.
Wiring harness damage (open, short, or chafed wires) between the pedal sensor and the ECM.
Poor electrical ground connection for the sensor circuit.
ECM software issue or internal fault (less common).
Aftermarket or incorrect pedal assembly installed.

How to diagnose and fix it

Use a BMW-specific scan tool to read fault memory and view live data for both pedal position sensor signals.
Visually inspect the pedal sensor connector and wiring for corrosion, damage, or loose pins; clean or repair as needed.
Check the sensor reference voltage and ground circuits with a multimeter to ensure they are within specification.
Perform a continuity and resistance test on the signal wires between the sensor and ECM to rule out wiring faults.
If wiring and connectors are good, replace the accelerator pedal assembly with a genuine BMW part.
After repair, clear fault codes and perform a throttle adaptation reset using the scan tool.
Road test the vehicle to verify the code does not return and that throttle response is normal.

Before you replace the accelerator pedal

A common misdiagnosis is replacing the pedal assembly when the real problem is a corroded connector or chafed wire in the harness, so always perform a thorough circuit test first.
The pedal position sensor uses two potentiometers with different voltage ranges; the ECM cross-checks them, so a fault in just one track can set P1543 without a complete failure.
Intermittent P1543 codes often occur due to water intrusion into the connector or pedal assembly, especially on vehicles with leaks or clogged sunroof drains.
A weak battery or charging system issue can cause voltage spikes that mimic sensor faults, so verify battery health and grounds before condemning the sensor.
After replacing the pedal or repairing wiring, a throttle adaptation reset is required; otherwise, the ECM may still store the code or run poorly.

Can I keep driving with P1543?

If the vehicle is in limp mode, driving is not recommended because acceleration is severely limited and could be unsafe in traffic. If the light is on but the car drives normally, you can drive cautiously to a repair shop, but avoid aggressive acceleration and be prepared for sudden power reduction.

Tools that help

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