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DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P057A

P057ABrake Pedal Position Sensor A Circuit/Open

P057A indicates that the powertrain control module (PCM) has detected an open circuit or abnormal voltage on the signal circuit of brake pedal position sensor A. The PCM expects a specific voltage range as the brake pedal moves, and a reading outside that range for a set time triggers this code. This sensor is critical for brake torque management, cruise control cancel, and shift interlock logic.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp) on the dashboard.
  • Often no symptoms besides the warning light, especially if the fault is intermittent.
  • Brake lights may fail to illuminate or may stay on continuously.
  • Cruise control may not engage or may disengage unexpectedly.
  • The transmission may not shift out of park or may exhibit harsh shifting.
  • Extended crank or no-start condition if the PCM relies on brake pedal status for starting logic.

Common causes, most likely first

  1. Open or damaged signal wire between the brake pedal position sensor and the PCM.
  2. Faulty brake pedal position sensor A (internal open circuit or worn contacts).
  3. Corroded, loose, or disconnected electrical connector at the sensor or PCM.
  4. Blown fuse or faulty ground connection shared by the sensor circuit.
  5. PCM software glitch or internal driver failure (rare but possible).
  6. Aftermarket accessories tapped into the brake pedal wiring causing interference.

How to diagnose and fix it

  1. Verify the code with a scan tool and check freeze-frame data for brake pedal position voltage.
  2. Inspect the brake pedal position sensor connector and wiring for corrosion, damage, or looseness.
  3. Measure reference voltage (typically 5V) and ground at the sensor connector with a digital multimeter.
  4. Perform a wiggle test on the harness while monitoring sensor voltage to detect intermittent opens.
  5. Check continuity of the signal circuit from the sensor to the PCM and repair any open or high-resistance wiring.
  6. Replace the brake pedal position sensor if the circuit tests good but the sensor output is erratic or absent.
  7. Clear the code and perform a road test to confirm the repair and ensure no pending codes return.

What Most Techs Miss on P057A

  • A misadjusted or loose brake pedal position sensor can set P057A without any visible wiring damage, so always check sensor mounting and calibration.
  • The brake pedal position sensor often shares a reference voltage with other sensors; a short in a unrelated component can pull down the 5V reference and set this code.
  • Aftermarket floor mats or pedal covers that restrict pedal travel can cause the sensor to read out of range and trigger P057A intermittently.
  • On some vehicles, a weak battery or poor ground can cause the PCM to misread the sensor signal, so always verify battery and ground integrity before replacing parts.
  • P057A can be set by a faulty brake light switch even if the brake lights work, because the switch may have multiple internal contacts for different circuits.

Can I keep driving with P057A?

The vehicle is generally safe to drive with P057A, but you should avoid relying on cruise control and be aware that brake lights or starting logic may be affected. Have the fault diagnosed promptly, especially if you notice brake light malfunction or shifting issues.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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