What it means
The control module detects a low signal in the Brake Pedal Position Sensor A circuit.
At a glance
- Usually lights the check-engine light
How it works
The control module monitors the signal from Brake Pedal Position Sensor A as the pedal moves. P057C sets when that signal is below the expected range, often because the signal wire is shorted to ground or a connector has a poor, resistive contact.
Common causes
Most likely first.
- Signal shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check-engine light may come on
- Cruise control may not engage or may disengage unexpectedly
- Brake lights may behave erratically
- Brake pedal position display or related system response may be inconsistent
How to diagnose it
- Record freeze-frame data and monitor the sensor A signal on a scan tool while pressing and releasing the brake pedal.
- Check brake-light behavior, then inspect the sensor A connector for corrosion, moisture, loose terminals, or pin push-back.
- Inspect the signal wire for chafing through its insulation and contact with ground.
- Use the wiring diagram to test the sensor A signal circuit for a ground short and check terminal contact quality.
- Test sensor output and module interpretation against the manufacturer's specification before replacing either component.
Common fixes
- Clean and secure corroded or loose sensor A connector terminals.
- Repair chafed signal wiring that is shorted to ground.
- Replace Brake Pedal Position Sensor A if its output remains low with a sound circuit.
- Repair or replace the related module if the sensor signal and wiring test correctly.
Can I keep driving?
The low signal can interfere with cruise cancellation and may affect brake-light or related system operation. Verify brake lights before driving, avoid cruise control, and do not drive if the lights or pedal behavior are unreliable.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.