Faulty accelerator pedal module or internal sensor track; Damaged wiring, chafing or broken wires between pedal and control unit; Corroded, loose or contaminated connector at the pedal or control unit; Poor sensor supply voltage or earth fault affecting the pedal sensor; Water ingress or damage in the footwell affecting the pedal module; Fault in the engine control unit.

P1543

Pedal Position Sensor.

BMW
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
5: AreaVehicle speed, idle control and auxiliary inputs
43: FaultThe specific fault in that area

What it means

On BMW, P1543 relates to the accelerator pedal position sensor (pedal value sender) circuit or signal. The engine control unit compares the two internal tracks of the pedal sensor and checks them against expected voltage ranges and each other. If a signal is out of range, implausible or the two tracks disagree, the code is stored. The exact fault description and test limits vary by model and engine control unit.

Symptoms

Engine warning light on
Car goes into limp mode with reduced power
Poor or delayed throttle response
Unstable or raised idle
Engine may not rev above a set limit
Cruise control not working

Possible causes

Faulty accelerator pedal module or internal sensor tracklikely
Damaged wiring, chafing or broken wires between pedal and control unitlikely
Corroded, loose or contaminated connector at the pedal or control unitpossible
Poor sensor supply voltage or earth fault affecting the pedal sensorpossible
Water ingress or damage in the footwell affecting the pedal modulepossible
Fault in the engine control unitrare

How to diagnose

Read all stored codes and freeze frame data, noting any related throttle or pedal codes
Check live data for both pedal sensor tracks and confirm they move smoothly and in step from released to fully pressed
Inspect the pedal module, connector and wiring for damage, moisture, corrosion or signs of rubbing
Wiggle test the harness and connector with live data displayed to look for dropouts
Check the sensor supply voltage and earth at the pedal connector against the manufacturer's data for that model
Test the wiring for continuity, short to earth and short to supply between pedal and control unit
Check the pedal moves freely and the mat or footwell items are not obstructing it
Check for software updates or technical bulletins applicable to the vehicle before considering the control unit

How to fix

Replace the accelerator pedal module if the sensor readings are faulty or implausible
Repair or replace damaged wiring and secure the harness away from rubbing points
Clean or replace corroded or damaged connector terminals
Correct supply or earth faults found during testing
Dry out and repair any water ingress source, replacing affected components
Update or replace the engine control unit only if testing proves it faulty or a known outdated software issue applies, then clear codes and road test

Can I keep driving?

Medium severity

The car may be in limp mode with limited power and unpredictable throttle response, which can be unsafe in traffic. Drive only if necessary and with care, and have it checked soon.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.