P0571 – Meaning, Symptoms, Causes & How to Fix It

P0571 can be annoying because it usually shows up right when you go to use cruise control and nothing happens. This code points to a problem in the brake switch circuit, which is how your car knows when your foot is on the brake pedal. While it rarely leaves you stranded, it can affect cruise control, brake lights, and safety systems. In this guide, you’ll learn what P0571 means, common symptoms, how a mechanic would diagnose it, and what it typically costs to fix.

What Does P0571 Mean?

P0571 is an OBD-II diagnostic trouble code that stands for “Brake Switch A Circuit Malfunction.” Your engine control unit (ECU) or body control module (BCM) sets this code when it sees an abnormal signal from the brake pedal switch circuit, usually the part labeled “A.”

This switch tells the car when you press the brake pedal so it can cancel cruise control, turn on the brake lights, and interact with ABS, traction control, and transmission logic. When the signal is out of range, missing, or inconsistent, the ECU flags P0571 and usually disables cruise control as a safety precaution.

Quick Reference

Code: P0571 – Brake Switch A Circuit Malfunction
Type: Electrical / signal fault in brake pedal switch circuit
Common Symptoms: Cruise control inoperative, brake lights issues, warning lights
Typical Causes: Faulty brake switch, misadjusted switch, wiring or connector problems
Risk Level: Low for engine damage, moderate for safety and drivability

Real-World Example / Field Notes

In the shop, I see P0571 most often on vehicles that come in with “cruise control stopped working” or “brake lights act weird.” A common case is a compact SUV where the customer reports the cruise light comes on but won’t set, and sometimes the brake lights stay on after parking. Scanning shows P0571 stored and sometimes a traction control light. A quick check at the brake pedal reveals a failing brake switch with intermittent internal contacts. Replacing and adjusting the switch clears the code and restores normal operation.

Symptoms of P0571

Cruise control inoperative – Cruise may not set at all, or it may drop out unexpectedly.
Brake lights malfunctioning – Brake lamps may stay on, not come on, or flicker when you hit bumps.
Warning lights on – You may see ABS, traction control, stability control, or “cruise” warning indicators.
Gearshift interlock issues – On some automatics, you may have trouble shifting out of Park if the system cannot see brake input.
Reduced driver aids – Systems like adaptive cruise, collision avoidance, or hill-start assist may be disabled.
Intermittent electrical glitches – Occasional chimes, messages like “Service Brake System,” or stored related codes.
Higher idle or odd transmission behavior – Some cars adjust idle or shift timing based on brake input and can behave oddly when the signal is wrong.

Common Causes of P0571

Most Common Causes

Faulty brake pedal switch – Internal wear, broken contacts, or contamination inside the switch is the number one cause. These switches see constant use and eventually fail.
Misadjusted brake switch – If the switch is not positioned correctly on the pedal bracket, it may not fully open or close, causing an incorrect signal to the ECU.
Loose or corroded connector at the brake switch – Moisture, spilled drinks, or previous repairs can leave the connector loose or corroded, creating intermittent voltage.
Blown brake light fuse or bulb issues – On some vehicles, the ECU monitors the brake light circuit; burned-out bulbs or a blown fuse can trigger P0571-related logic faults.
Wiring damage near the pedal area – Harnesses can be kicked, pinched, or rubbed through by pedal movement or aftermarket accessories.

Less Common Causes

Faulty brake pedal position sensor – Some modern cars use a more advanced sensor in addition to or instead of a simple on/off switch.
Aftermarket accessories spliced into brake circuit – Trailer brake controllers, remote start systems, or alarm installs can introduce wiring faults.
Internal ECU or BCM fault – Rare, but possible if all wiring and switch tests good and other related codes are present.
Water intrusion in cabin junction block – Leaks at the windshield or firewall can corrode fuse boxes and connectors feeding the brake switch circuit.
Incorrect parts installed – Using the wrong brake switch or miswired replacement can cause constant or missing brake signal.

Diagnosis: Step-by-Step Guide

You’ll want a basic scan tool (preferably one that can read live data), a digital multimeter, a test light, and basic hand tools. Access to wiring diagrams or service information for your specific vehicle is very helpful. If your scan tool supports Mode $06 data, you can sometimes see detailed test results for the brake switch circuit.

Confirm the code and check for companions
Plug in your scan tool, confirm P0571 is present, and look for related codes like brake light circuit, ABS, or cruise control codes. Note whether the code is current or stored as history.
Check brake light operation
With the ignition on, press and release the brake pedal. Verify if the brake lights come on and go off correctly. Have someone watch the lights or back up near a reflective surface. Any delay, flicker, or no response is a big clue.
Inspect the brake switch and mounting
Look up under the dash at the top of the brake pedal. Locate the switch and its connector. Check for broken plastic, loose mounting, misalignment with the pedal, or physical damage from feet or aftermarket parts.
Check the connector and wiring
Unplug the connector and inspect for corrosion, bent pins, moisture, or loose terminals. Gently tug on the wires to see if any are broken inside the insulation. Repair any obvious wiring damage before going deeper.
Test power and ground at the switch
Using a multimeter or test light, verify that you have proper battery voltage on the supply wire with the ignition on, and a good ground where applicable. If power or ground is missing, trace back to the fuse box or junction block.
Check switch output signal
With the connector plugged in (back-probed) or the switch bench-tested, monitor the output wire while pressing and releasing the pedal. You should see a clean change from 0 V to battery voltage (or vice versa) with pedal movement. Any erratic or no change indicates a bad switch or misadjustment.
Verify switch adjustment
Many switches are adjustable by threading in or out or by a locking collar. Follow service info to set the correct gap or position so the switch changes state right as the pedal moves. An incorrectly adjusted switch can appear “bad” when it’s just out of position.
Use scan tool live data
Look at the brake switch or brake pedal status PIDs in the scan tool. Press and release the pedal and confirm that the ECU sees the change instantly. If the switch tests good electrically but the ECU doesn’t see it, suspect wiring between the switch and control module.
Check for advanced issues (if needed)
If all tests pass, inspect for water intrusion at fuse boxes, splice points, and the BCM/ECU connectors. At this stage, a professional-level scan tool and wiring diagrams are usually required.
Clear codes and road test
After repairs or adjustments, clear P0571 and test-drive the vehicle. Verify cruise control, brake lights, and any warning lights are operating normally.

Pro tip: On many vehicles, a failing brake switch will set P0571 long before it completely dies. If you see intermittent P0571 and slightly odd brake light behavior, replacing the switch proactively can save you from being stuck without cruise or with brake lights stuck on.

Possible Fixes & Repair Costs

Most P0571 repairs are straightforward and not very expensive compared to major engine or transmission work. The exact cost depends on your vehicle, parts quality, and labor rates in your area.

Replace brake pedal switch – The most common fix. Parts typically run $20–$100. Labor is usually 0.5–1.0 hour, so at a shop you might see $100–$250 total.
Adjust or reinstall brake switch – If the switch is good but misadjusted, a simple adjustment may solve it. This can be a minimal labor charge, around $50–$120 depending on shop minimums.
Repair wiring or connector – Fixing broken wires, corroded terminals, or damaged connectors can cost $100–$300, depending on how deep the harness is and how much disassembly is needed.
Replace bulbs, fuses, or junction components – If the issue is related to the monitored brake light circuit, parts are cheap ($5–$40) with minor labor.
Control module issues – Very rare for this code, but if the BCM or ECU is at fault, costs can jump to $500–$1,200+ including programming.

Typical overall repair cost for P0571 is in the $120–$350 range for most vehicles when it’s just the switch or a minor wiring issue. Luxury or European models, or those requiring dash disassembly, may run higher.

Can I Still Drive With P0571?

In most cases, you can still drive with P0571 without risking engine damage, but there are safety considerations. Cruise control may not work, and your brake lights might not function correctly or could stay on. That means drivers behind you may not know when you are braking, and you might get pulled over or fail a safety inspection.

Short trips to get the vehicle inspected or repaired are usually fine, but you should avoid night driving or heavy traffic until you’re sure the brake lights are working correctly. If the brake lights do not work at all, the car really should not be driven on public roads.

What Happens If You Ignore P0571?

If you ignore P0571, you risk driving without proper brake light function and with disabled safety systems like cruise control and possibly traction or stability control. Over time, a marginal switch can fail completely, leaving you with no brake lights and potential legal and safety issues. It’s not an engine-killer code, but it can absolutely create dangerous situations in traffic.

Last updated: March 1, 2026

Key Takeaways

P0571 means the ECU has detected an abnormal signal in the “Brake Switch A” circuit.
The most common cause is a worn or misadjusted brake pedal switch, often affecting cruise control and brake lights.
Diagnosis focuses on checking brake light operation, switch adjustment, wiring, and live data.
Repairs are usually affordable, often under a few hundred dollars at a typical shop.
You can usually drive with P0571, but only if your brake lights are confirmed to be working correctly.

Vehicles Commonly Affected by P0571

P0571 can appear on almost any OBD-II vehicle, but it’s especially common on certain makes and models where the brake switch design or location leads to premature wear. In the field, I often see this code on:

Volkswagen and Audi – Jetta, Golf, Passat, A3, A4; many have known brake switch issues and recalls.
GM vehicles – Chevrolet Silverado, Malibu, Equinox, GMC Sierra, and Buick sedans often show brake switch and cruise-related faults.
Ford and Lincoln – Focus, Fusion, Escape, F-150, and related SUVs can log P0571 when the switch or wiring ages.
Hyundai and Kia – Elantra, Sonata, Tucson, Optima, and Sorento have had brake switch campaigns in some years.
Honda and Acura – Civic, Accord, CR-V, and MDX occasionally set this code with worn switches.
Toyota and Lexus – Camry, Corolla, RAV4, and RX may show P0571 when the stop light switch or connector fails.

Trucks, SUVs, and vehicles with towing packages are also more likely to have wiring modifications or trailer harnesses tied into the brake circuit, which can contribute to P0571 if not installed correctly.

FAQ

Can P0571 cause my cruise control to stop working?

Yes. When the ECU detects a fault in the brake switch circuit, it usually disables cruise control as a safety measure. The system must be absolutely sure it can detect brake pedal input, so any abnormal signal from the switch will prevent cruise from setting or staying engaged.

Is P0571 dangerous to drive with?

It can be, depending on how it affects your brake lights. If the brake lights do not work or stay on constantly, other drivers cannot accurately see when you are braking, which is a serious safety risk. If your brake lights function correctly, the main issue is loss of cruise control and possibly some driver-assist features, but you should still repair it soon.

How do I know if my brake switch is bad or just misadjusted?

If the brake lights are stuck on or never come on, and gentle movement of the switch or pedal area makes them flicker, the switch is usually failing internally. If the switch looks new or was recently replaced and only works when the pedal is in an odd position, it may just be out of adjustment. A quick electrical test with a multimeter while moving the pedal will tell you whether the switch contacts are reliable.

Can I replace the brake pedal switch myself?

On many vehicles, yes. The brake switch is often held by a clip, nut, or twist-lock mount on the pedal bracket. If you’re comfortable working under the dash and following basic instructions, you can usually replace it with simple tools. The critical part is adjusting it correctly and verifying brake light operation before driving.

Does clearing P0571 with a scanner fix the problem?

No. Clearing the code only erases the stored fault information from the ECU’s memory. If the underlying issue with the brake switch, wiring, or adjustment is still there, P0571 will return, sometimes immediately. Always diagnose and repair the root cause before relying on a cleared code as “fixed.”

P0571 – Brake Switch “A” Circuit