EngineLightCodes
Powertrain code

P0571 Brake Switch A Circuit

Severity
Fix soon
Typical repair cost
$20–$130
Do it yourself
Possible, easy
Shop time
0.3–1 hours

Brake switch A is the brake light switch or its signal to the engine module.

How the engine computer detects it

The module needs it to cancel cruise control and for brake-throttle override, stop-start, idle control and the shift interlock. As cruise control is simply switched off, CARB treats such faults as emission-neutral – usually without warning lamp. P0571 is the general fault, usually detected by plausibility: Saab's 3.0 TiD (Bosch) sets it when the car brakes three times from over 49 km/h (30 mph) to standstill at 1.6 m/s² or more without a switch signal; Bosch EDC16 then switches cruise control off. NHTSA found Hyundai and Kia setting P0571 with P0504 from misadjusted brake light switches. Ford and GM gasoline engines use P0572/P0573 instead.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Cruise control cannot be set or switches off
  • Brake lights not working or permanently on
  • Possibly ABS/ESC warning (Hyundai/Kia)

Common causes

  1. Brake light switch misadjusted Most likely
  2. Brake light switch faulty (worn contact) Most likely
  3. Connector, wire or brake light fuse Possible
  4. Engine or body module Less likely

How to diagnose P0571

  1. Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
  2. Inspect the parts involved: brake switch, brake light fuse, switch wiring, engine control module.
  3. Work through the causes above from most to least likely, cheapest checks first.
  4. Clear the code and drive a full drive cycle to confirm the repair held.

Reading the code

P
Powertrain
0
Generic (SAE) code
5
Vehicle speed, idle control and auxiliary inputs
71
Specific fault

Questions drivers ask

Can I drive with code P0571?

Usually yes, carefully. Your hydraulic brakes normally keep working, but ABS, traction and stability control may be off, so the wheels can lock in a hard stop. If the red brake warning light is on, the pedal feels soft or different, or the car takes longer to stop, don't drive: have it towed.

Can I fix P0571 myself?

Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.