OBD-II Code P0571 — What It Means & How to Fix It

What Does This Error Mean?

P0571 means there is a problem with the brake switch circuit — specifically Switch A. The brake switch tells the engine computer and other systems when you press the brake pedal. This signal is used by cruise control, brake lights, the torque converter clutch, and ABS. When this switch fails, your cruise control may not cancel when you brake, or your brake lights may not work. This code should be addressed promptly because brake lights are a safety item.

Affected Models

All vehicles 1996+
Common in Ford and Lincoln vehicles
Common in GM cars and trucks
Common in Chrysler, Dodge, and Jeep vehicles
Common in Toyota and Honda vehicles

Common Causes

Faulty brake light switch on the brake pedal that has worn out or failed
Misadjusted brake switch that does not activate at the right pedal position
Damaged or corroded wiring to the brake switch
Blown fuse in the brake switch circuit
Corroded or loose brake switch connector

How to Fix It

Check your brake lights first. Have someone stand behind the car while you press the brake pedal. If the brake lights do not come on, the brake switch is the likely culprit.

Also check the brake light fuse in the fuse box before replacing the switch.
Locate the brake switch under the dashboard, above the brake pedal. It is a small switch that contacts the pedal arm when the pedal is released.

You may need a flashlight to see it clearly. It usually clips or threads into a bracket near the top of the pedal.
Check that the brake switch is properly adjusted. The switch should just contact the pedal arm when the pedal is at rest. Turn the switch adjustment if your design allows it.

Many brake switches thread in and out for adjustment. One to two turns can make a big difference.
Unplug the switch connector and test the switch with a multimeter. With the pedal released, the switch should show continuity (or open — depending on design). Press the pedal and confirm the state changes.

Your repair manual will tell you what the switch should read in each position.
Replace the brake switch if it is faulty or out of adjustment and cannot be corrected. Clear the code and verify brake lights work and cruise control cancels properly when braking.

After replacement, double-check cruise control function on a safe stretch of road before returning to normal driving.

When to Call a Professional

Brake switch replacement is one of the easiest DIY repairs on most vehicles. Brake switches cost $10 to $40 for the part. Labor at a shop is $50 to $100 since the switch is accessible under the dash. Total repair at a shop is typically $60 to $140. Always verify brake lights work after replacement — this is a safety-critical item.

Frequently Asked Questions

Are my brake lights working if I have P0571?

Not necessarily. P0571 can occur even if the brake lights still work — depending on which circuit has failed. But always check your brake lights immediately when this code appears. Brake lights are a safety item that can prevent rear-end collisions.

Will P0571 affect my cruise control?

Yes. The brake switch signal cancels cruise control when you press the brake pedal. If the switch is faulty, cruise control may not cancel when braking — a serious safety concern. Cruise control may also refuse to engage as a safety measure.

Is a brake switch easy to replace at home?

Yes, it is one of the easier repairs on most cars. The switch is usually accessible under the dash without any tools needed for removal. Most switches simply twist or unclip to remove. The job typically takes 15 to 30 minutes.