Damaged, chafed or corroded wiring or connector at the brake pedal position sensor (short to ground or open circuit); Faulty brake pedal position sensor; Sensor misaligned, loose or mechanically disturbed at the pedal assembly, for example after pedal or trim work; Loss of sensor reference supply or poor ground from the control unit circuit; Low battery voltage or poor power and earth connections affecting the sensor circuit; Fault inside the engine or brake control module.

P057C

Brake Pedal Position Sensor A Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
7C: FaultThe specific fault in that area

What it means

P057C means the control unit has seen the signal from brake pedal position sensor A at a voltage lower than the expected range. The sensor measures how far the pedal is pressed, and a low reading suggests a short to ground, an open circuit, a lost supply or a failed sensor. The exact sensor location and which module monitors it vary by model.

Symptoms

Engine warning light on
Brake lights not working, or staying on
Cruise control or speed limiter unavailable
Reduced engine power or limited response
Stop-start disabled
Difficulty starting on push-button start cars, or the system not recognising the brake pedal

Possible causes

Damaged, chafed or corroded wiring or connector at the brake pedal position sensor (short to ground or open circuit)likely
Faulty brake pedal position sensorlikely
Sensor misaligned, loose or mechanically disturbed at the pedal assembly, for example after pedal or trim workpossible
Loss of sensor reference supply or poor ground from the control unit circuitpossible
Low battery voltage or poor power and earth connections affecting the sensor circuitpossible
Fault inside the engine or brake control modulerare

How to diagnose

Read all stored and pending codes and record the freeze frame data, noting any related brake switch, cruise or stability control codes.
Check the brake lights work correctly and that the pedal moves freely and returns fully.
Inspect the sensor, its connector and the wiring for damage, water ingress, corrosion, chafing or bent pins.
With a scan tool, watch the brake pedal position live data while pressing and releasing the pedal, and look for a stuck, low or erratic reading.
Check battery condition and charging voltage, as low voltage can upset sensor readings.
With the connector unplugged, check the reference supply and ground at the sensor against the manufacturer's wiring diagram and specification.
Check the signal wire for continuity, and for shorts to ground or to other wires.
Check the sensor mounting and adjustment against the manufacturer's procedure for that model.

How to fix

Repair or replace damaged wiring, and clean or replace corroded or damaged connectors.
Replace the brake pedal position sensor if it fails the signal checks.
Refit, reposition or adjust the sensor as the manufacturer specifies, and perform any required calibration or learning procedure.
Restore the sensor supply or ground circuit, including any poor earth connection.
Repair the battery or charging fault, then clear the codes and road test to confirm the fault does not return.

Can I keep driving?

Medium severity

The car may be driveable, but faulty brake light operation is a safety and legal concern and reduced power or limited functions may occur. Have it checked soon, and stop driving if the brake lights are not working.

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