P057DBrake Pedal Position Sensor "A" Circuit High
The brake pedal position sensor signal voltage is stuck above its normal operating range.
Definition
The PCM expects the brake pedal position sensor's analog output to remain inside a defined window through pedal travel, and P057D sets when the signal exceeds the maximum threshold — typically from a short to voltage, an open ground circuit, or a failed sensor. Depending on the design, the module may interpret the high signal as constant full braking, disabling cruise control, triggering brake-override throttle limiting, keeping brake lights on, or limiting regenerative braking on hybrids. Push-button start systems may also refuse to recognize a pedal press.
Common causes
- Open sensor ground circuit driving the signal high
- Signal wire shorted to the 5 V reference or battery voltage
- Failed brake pedal position sensor
- Corroded connector terminal breaking the ground path
- Chafed harness contacting a powered circuit
- Faulty control module input (rare)
Common misdiagnoses
- Replacing the brake light switch for brake lights stuck on
- Replacing the sensor when the ground circuit is open
- Replacing the throttle body for brake-override power loss
- Replacing the ABS module
Troubleshooting steps
1.Confirm the high signal on a scan tool
A BPP reading pegged at maximum (or near 5 V) regardless of pedal position confirms the electrical fault.
2.Check the sensor ground circuit
Measure voltage between the sensor ground terminal and battery negative with the key on; more than 0.1 V indicates a poor or open ground.
3.Test for a short to voltage
If the signal stays high with the sensor disconnected, the harness signal wire is shorted to a voltage source — trace and repair it.
4.Inspect the connector and harness
Look for corrosion, spread terminals, and chafe points where the pedal-area harness can touch powered circuits.
5.Replace the sensor if circuits test good
With supply, ground, and signal wiring verified, replace the sensor and complete any pedal zero-point calibration before final road test.