Brake switch A is the brake light switch or its signal to the engine module. 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 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 petrol engines use P0572/P0573 instead.
Medium severity. Can I keep driving?First check that the brake lights work: if they do not come on, get them repaired before driving because you risk being rear-ended. If they work, you can go to a repair shop, knowing that cruise control and other aids may not be active.
Symptoms
- Cruise control cannot be set or switches off
- Brake lights not working or permanently on
- Possibly ABS/ESC warning (Hyundai/Kia)
Most likely causes
- Brake light switch misadjusted
- Brake light switch faulty (worn contact)
- Connector, wire or brake light fuse
- Engine or body module
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
What each character of P0571 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 5: Speed and idle
- 71: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0571?
First check that the brake lights work: if they do not come on, get them repaired before driving because you risk being rear-ended. If they work, you can go to a repair shop, knowing that cruise control and other aids may not be active.
What causes code P0571?
The most common causes are: brake light switch misadjusted; brake light switch faulty (worn contact); connector, wire or brake light fuse.
Related codes
- P0572Brake Switch A Circuit Low
- P0573Brake Switch A Circuit High
- P0504Brake Switch A/B Correlation
- P0703Brake Switch B Circuit
Sources
- saabwisonline.com: p0571
- saabwisonline.com: p0571 01
- static.nhtsa.gov: INRD PE09003 36683
- law.cornell.edu: 13 CCR 1968.2
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.