P057B: Brake Pedal Position Sensor A Circuit Range/Performance
What to do
Your brakes still work normally — this is a sensing fault, not a braking one. What you will lose is cruise control, and on a hybrid or electric car the regenerative braking, so the car may feel like it slows differently and the brake pedal may feel firmer or less familiar. Allow for that.
Mention whether the brake lights work correctly, including going off promptly when you release the pedal. The module cross-checks this sensor against the brake light switch, and a switch out of adjustment can cause the disagreement.
Say if cruise control has stopped working or disengages by itself, which fits this fault.
Do not delay the repair. Driver assistance systems that rely on knowing you are braking will be switched off until it is fixed.
What this code means
The brake pedal position sensor is reporting a value that is electrically valid but does not fit.
A brake pedal position sensor is a different thing from a brake light switch, and the difference is why this code matters more than it looks. A switch answers yes or no. A position sensor reports how far — proportionally, continuously, throughout the pedal's travel.
That proportional signal is used for things a switch could never serve:
- Regenerative braking blending on hybrids and electric vehicles. The car decides how much retardation comes from the motor and how much from the friction brakes, and it needs to know how hard you are pressing.
- Brake override, which cuts throttle when brake and accelerator are applied together.
- Adaptive cruise and emergency braking, which need to know whether the driver is already braking and how much.
Range/performance means the signal is present and does not agree with the rest of the picture — usually the brake light switch, since the module cross-checks the two and they must move together.
A sensor that has drifted at the rest position is the usual finding, and it is worth knowing why: the pedal sits at rest for almost its entire life, so that is where a resistive track wears.
Expect the vehicle to disable regenerative braking, cruise control and driver assistance rather than risk acting on a signal it cannot trust. The brakes themselves are unaffected — this is a sensing fault, not a braking one.
Likely causes
Start here
- Faulty brake light switch · easy
- Faulty brake pedal position sensor · moderate
Less common
- Corroded or loose connector · easy
- Sensor calibration not performed after repair · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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