Faulty brake switch (both sources). Wiring problem, such as a wire pinched at the brake pedal or chafed (both sources). Faulty engine computer (PCM/ECM), less common (both sources). Brake switch out of adjustment (OBD-Codes.com). Brake switch knocked out of its mount or broken off (OBD-Codes.com). Dirt or debris stopping the switch from moving (OBD-Codes.com).

Replace the brake switch, following the manufacturer's install and adjustment procedure (both sources). Re-mount or adjust a switch that has come loose or is misadjusted (OBD-Codes.com). Repair pinched, chafed or corroded wiring and clean corroded connector pins (both sources). Repair or replace the engine computer (or body control module where it runs cruise control) only after the switch and wiring test good (both sources).

P0571🔧 Brake pedal switch / cruise controlStop and fix promptly

P0571: Brake Switch A Circuit (Meaning, Causes, Fixes)

Q: What does P0571 mean?

P0571 means the engine computer found a problem with the brake switch 'A' circuit, the switch that tells it you're pressing the brake pedal and usually also turns on the brake lights. The most common results are cruise control that won't work and, if the switch itself has failed, brake lights that stay off. Common causes are a faulty or misadjusted brake switch, damaged wiring near the pedal and, less often, the engine computer. The brake switch sits on the brake pedal arm under the dash. It tells the engine computer when the pedal is pressed so cruise control can switch off, and on most cars it also powers the brake lights. RepairPal says P0571 sets when the computer sees the vehicle slowing down without the brake switch reporting that the pedal is pressed. OBD-Codes.com describes it more broadly as the computer detecting a malfunction anywhere in the cruise control/brake switch 'A' circuit, and says the 'A' may refer to a specific wire, connector or harness that only your service manual can identify. The sources also word the code differently: OBD-Codes.com calls it 'Cruise Control/Brake Switch A Circuit Malfunction', while RepairPal uses 'Brake Switch "A" Circuit'. OBD-Codes.com lists P0572 and P0573 as related codes, and notes that on some cars the body control module (BCM), not the engine computer, runs cruise control. It is a generic code that can appear on any OBD-II vehicle.

Q: Can I keep driving with P0571?

Stop and fix promptly. Check your brake lights before driving. The same brake pedal switch usually turns on your brake lights, and both sources list brake lights not working as a possible symptom, which means drivers behind you may not see you slowing down. RepairPal rates P0571 Urgent. OBD-Codes.com calls it moderately severe, explaining that cruise control faults are usually low priority but a possible brake switch problem is a real safety concern. If your brake lights don't come on, don't drive until it's fixed, and don't rely on cruise control.

Reviewed 2026-10-23 · Based on 2 cited source(s)

What P0571 means

The brake switch sits on the brake pedal arm under the dash. It tells the engine computer when the pedal is pressed so cruise control can switch off, and on most cars it also powers the brake lights. RepairPal says P0571 sets when the computer sees the vehicle slowing down without the brake switch reporting that the pedal is pressed. OBD-Codes.com describes it more broadly as the computer detecting a malfunction anywhere in the cruise control/brake switch 'A' circuit, and says the 'A' may refer to a specific wire, connector or harness that only your service manual can identify. The sources also word the code differently: OBD-Codes.com calls it 'Cruise Control/Brake Switch A Circuit Malfunction', while RepairPal uses 'Brake Switch "A" Circuit'. OBD-Codes.com lists P0572 and P0573 as related codes, and notes that on some cars the body control module (BCM), not the engine computer, runs cruise control. It is a generic code that can appear on any OBD-II vehicle.

Severity: can I keep driving?

Stop and fix promptly

Check your brake lights before driving. The same brake pedal switch usually turns on your brake lights, and both sources list brake lights not working as a possible symptom, which means drivers behind you may not see you slowing down. RepairPal rates P0571 Urgent. OBD-Codes.com calls it moderately severe, explaining that cruise control faults are usually low priority but a possible brake switch problem is a real safety concern. If your brake lights don't come on, don't drive until it's fixed, and don't rely on cruise control.

Common symptoms

Cruise control not working at all (both sources)
Brake lights not coming on if the switch is faulty (both sources)
Erratic cruise control, or cruise that turns on but won't engage (OBD-Codes.com)
Cruise buttons like set, resume or accelerate not working properly (OBD-Codes.com)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Faulty brake switch (both sources)
Wiring problem, such as a wire pinched at the brake pedal or chafed (both sources)
Faulty engine computer (PCM/ECM), less common (both sources)
Brake switch out of adjustment (OBD-Codes.com)
Brake switch knocked out of its mount or broken off (OBD-Codes.com)
Dirt or debris stopping the switch from moving (OBD-Codes.com)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Have someone watch the rear of the car while you press the brake pedal. If the brake lights don't come on, the switch or its wiring is a strong suspect, and it's a safety issue to fix right away.
Look under the dash at the switch on the brake pedal arm. OBD-Codes.com says a driver's foot sometimes knocks the switch out of its mount or breaks it off, which you can see right away.
Check that the switch is adjusted correctly and that nothing is stopping it from moving freely (OBD-Codes.com).
Inspect the wiring and connector at the switch for pinched, chafed or corroded wires. OBD-Codes.com suggests a continuity test of the circuit with a multimeter, using your service manual's wiring diagram and specs.
Check for technical service bulletins (TSBs) for your vehicle, which OBD-Codes.com recommends as the first step.

Typical fixes

Replace the brake switch, following the manufacturer's install and adjustment procedure (both sources)
Re-mount or adjust a switch that has come loose or is misadjusted (OBD-Codes.com)
Repair pinched, chafed or corroded wiring and clean corroded connector pins (both sources)
Repair or replace the engine computer (or body control module where it runs cruise control) only after the switch and wiring test good (both sources)

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

Your brake lights don't work and you can't fix the switch yourself
The switch needs a specific adjustment procedure you don't have
Wiring tests point to the engine or body control module
The code comes back after a new, properly adjusted switch

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with P0571?

First check that your brake lights work. If they don't, get it fixed before driving, since drivers behind you won't see you braking. RepairPal rates P0571 Urgent and OBD-Codes.com calls it moderately severe.

Why did my cruise control stop working?

The computer needs the brake switch signal to know when to cancel cruise. When it sees a fault in that circuit, cruise control often stops working, which both sources list as a symptom.

Is the brake switch the same as the brake light switch?

On many cars, yes. RepairPal says the brake switch also controls the brake lights, and OBD-Codes.com says one of its functions is turning on the rear brake lights.

How much does it cost to fix P0571?

Neither source gives a repair cost for P0571. It can range from re-mounting or adjusting the switch to replacing it or repairing wiring, so diagnose it first.

Sources

Last reviewed 2026-10-23. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.