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P0571 almost always points to the brake light switch above the brake pedal. $15 part, 10-minute fix on most cars. If your brake lights are stuck on or your cruise won't set, that's the same switch. Verify with a scan tool watching the brake switch PID as you press the pedal. See top-rated scanners on Amazon ↗
🗺 Where Is the Problem?
Blueprint view - P0571 system overview
These are statistical causes across ALL vehicles - your exact car may rank differently
For example, on a Honda 4-cyl the downstream O2 sensor causes P0571 64% of the time, but on a GM 5.3L V8 the catalytic converter is the cause 71% of the time. Get a probability ranking built specifically for your year, make, model, and mileage.
🔎 Get the ranking for my exact car - $5.99 →
🎯 Top Causes & Probability
75%
#1 - Most Likely
Faulty Brake Light Switch
The mechanical switch above the brake pedal sticks, has worn contacts, or its plunger has snapped (common on Toyota and GM after 100k miles). Replacement is fast and cheap. Adjust per the FSM after install.
🔩 Part
$10–$40
👨🔧 Labor
$20–$80
⚡ DIY Difficulty
Easy
15%
#2 - Check Second
Wiring or Connector Issue
Corroded pins at the switch connector or chafed wires under the dash. Inspect with the connector unplugged and check for green corrosion or bent pins.
🔩 Part
$5–$30
👨🔧 Labor
$40–$120
⚡ DIY Difficulty
Easy
10%
#3 - Less Common
Cruise Control Module / Stalk
Less common - a failed cruise stalk or cruise control module can throw P0571 indirectly. Diagnose only after ruling out the switch and wiring.
🔩 Part
$60–$250
👨🔧 Labor
$60–$200
⚡ DIY Difficulty
Medium
🚗 Most Affected Vehicles
🔧 Step-by-Step Diagnosis
- Watch Brake Switch PID - With a scan tool, view the brake switch PID. Press the brake pedal: should toggle ON/OFF cleanly. If it doesn't change or flickers, the switch is bad.
- Verify Brake Lights - Check the brake lights with a helper. Stuck on, stuck off, or intermittent - all common signs of a failed switch. Replace and adjust the plunger per spec.
📍 Find a Trusted Shop Near You
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Tips for Choosing a Shop
- Ask if they charge a diagnostic fee and whether it applies toward the repair
- Request a written estimate before approving any work
- Ask specifically about the part brand - OEM vs. aftermarket matters for this code
- Check Google reviews for recent mentions of the specific repair you need