P0571

Brake Switch A Circuit

Cruise control / brake switch Generic OBD-II Low

What it means

P0571 means the ECM has seen an implausible signal from the brake pedal switch, the switch that also feeds cruise control, the brake lights, and the shift interlock. It's most often a failed or misadjusted brake light switch. The car drives normally, but cruise control may be disabled and brake-light behaviour can be affected, which makes it a safety-relevant fix.

Low

Can I keep driving? Drivable — the engine runs fine, but cruise control may not work and the brake-light/shift-interlock functions can act up; fix it soon for safety and convenience.

Real-world scan data

Seen in

2,948

scans in the past year

Found in

0.5%

of scans

0.8%

of scans that found faults

Appears alongside · share of P0571 scans

P0683in 45.4% of scans

P0110in 34.0% of scans

P0100in 28.1% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Cruise control won't set, or disengages on its own
Brake lights that don't come on, stay on, or work erratically
Shift interlock issue — can't move the shifter out of Park
Check-engine light on

Common causes

Most likely first

Faulty or misadjusted brake light switch (the most common cause)Likely
Blown brake-light fuse or wiring fault in the switch circuitCommon
Loose or corroded connector at the brake switchCommon
Two brake switch inputs disagreeing (redundant switch signal mismatch)Less often
Faulty engine control module (ECM), rareLess often

How to diagnose & fix

Work through it in order

Inspect and test the brake light switch — confirm the brake lights work when the pedal is pressed.
Check the brake-switch adjustment and the pedal striker; readjust if the switch isn't fully actuated.
Check the brake-light fuse and the switch connector for damage or corrosion.
Back-probe the switch signal to the ECM to confirm it changes state with the pedal.
Replace the brake switch if it tests faulty. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0571?+

The engine and brakes still work, but faulty brake-light signaling is a safety issue — other drivers may not see you braking. Get the switch checked promptly.

Can I just clear P0571?+

It will return until the switch or its wiring is fixed. Many cars also block cruise control and shifting out of Park while this fault is active.

Read & clear P0571 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX