Speed, idle & inputs · Powertrain · generic (SAE-defined)
P0571: Brake Switch "A" Circuit
P0571 means the engine computer has detected a problem with the brake pedal switch circuit, which tells it when the brakes are applied.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0571 sets
The powertrain control module (PCM) reads one or more brake switch signals to manage cruise control, torque converter clutch release, shift interlock, and brake-throttle override. If the switch signal is missing, stuck, or disagrees with a second switch or brake pressure input, the PCM sets P0571. The monitoring method varies by manufacturer.
Common causes of P0571
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Faulty or misadjusted brake pedal switch
- Broken plastic plunger or stopper pad at the pedal
- Damaged wiring or connector at the switch
- Blown brake light fuse
- Burned-out brake light bulbs on some designs
P0571 symptoms
- Check engine light on
- Cruise control not working
- Brake lights not working or staying on
- Shift lever stuck in park on some vehicles
- Torque converter clutch not releasing properly
How P0571 is diagnosed
- Check that brake lights turn on and off with the pedal
- Inspect the switch, its adjustment, and the pedal stopper pad
- Check the brake light fuse
- Watch brake switch status in live data while pressing the pedal
- Test switch continuity and wiring to the PCM
Typical fixes for P0571
- Replace the brake pedal switch
- Adjust the switch or replace a missing stopper pad
- Repair wiring or connectors
- Replace a blown fuse after finding the cause
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Definitions can vary by manufacturer; check factory service information. Older SAE wording is "Cruise Control/Brake Switch A Circuit Malfunction."
Related codes & warning lights
P0571 FAQ
What does code P0571 mean?
P0571 means the engine computer has detected a problem with the brake pedal switch circuit, which tells it when the brakes are applied. The standard definition is "Brake Switch "A" Circuit."
Can I drive with a P0571 code?
Check that your brake lights work before driving. If they do not, have it fixed before driving, because following drivers will not see you braking. Cruise control will likely be disabled, and some vehicles may not shift out of park until the switch is repaired.
Why doesn't my cruise control work with P0571?
The computer needs a reliable brake switch signal to cancel cruise control safely, so it disables cruise when the switch circuit is faulty.
Can a missing pedal bumper cause P0571?
Yes. On many vehicles a small rubber or plastic bumper on the pedal arm presses the switch, and if it falls out, the switch reads incorrectly.
Keep researching
More speed, idle & inputs codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.