P0571
Brake Switch A Circuit
If your code reader dashboard displays the generic DTC error code P0571, your vehicle is currently experiencing an active failure related to "Brake Switch A Circuit". Proper system troubleshooting is required to safely clear this warning.
Driver's Summary
The diagnostic trouble code P0571 indicates an active fault in the brake switch a circuit circuit or component. Drivers typically experience cruise control won't engage, brake lights stay on or won't turn on, shift interlock stuck when this code is active. This is a moderate-severity fault — plan a repair shop visit within the week to keep it from escalating.
Symptoms
Cruise control won't engage, brake lights stay on or won't turn on, shift interlock stuck
Common Causes
- Misadjusted brake light switch
- Failed brake light switch
- Blown brake light fuse
- Damaged wiring to switch
How to Fix
- 1 Adjust brake switch depth
- 2 Replace brake pedal switch
- 3 Check and replace related fuses
- 4 Repair wiring harness
Technical Explanation
Detection of P0571 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. A two-trip detection strategy is employed for most powertrain codes: the fault must be detected on one drive cycle, the vehicle key-cycled off, and the fault detected again on the next drive cycle before the MIL illuminates and a permanent DTC is stored. The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
Code P0571 allows for cautious short-distance driving, but the underlying cause — most likely misadjusted brake light switch — will worsen with time. Fuel economy suffers, and ignoring the fault for weeks can turn a $10 fix into a much larger repair bill.
Mechanic's Pro Tip
Before replacing any component on P0571, spend 5 minutes inspecting the wiring harness and connector first — corrosion, chafed insulation, and backed-out pins cause the majority of these faults and cost nothing to fix. Use a multimeter to measure voltage drop across the connector pins under load; anything above 0.1V indicates excessive resistance that will cause intermittent failures even after replacing the sensor.
Related Fault Codes
Frequently Asked Questions
What does OBD2 code P0571 mean?
OBD2 code P0571 refers to Brake Switch A Circuit. If your code reader dashboard displays the generic DTC error code P0571, your vehicle is currently experiencing an active failure related to "Brake Switch A Circuit". Proper system troubleshooting is required to safely clear this warning.
What are the most common symptoms of DTC P0571?
Drivers experiencing code P0571 typically report: Cruise control won't engage, brake lights stay on or won't turn on, shift interlock stuck.
Is it safe to drive with trouble code P0571 active?
Code P0571 allows for cautious short-distance driving, but the underlying cause — most likely misadjusted brake light switch — will worsen with time. Fuel economy suffers, and ignoring the fault for weeks can turn a $10 fix into a much larger repair bill.
How much does it cost to fix code P0571?
The estimated repair cost for P0571 ranges from $10 to $150 USD. Fuse: $10; Brake switch: $50 - $150
Fuse: $10; Brake switch: $50 - $150
Need Professional Diagnostic Assistance?
Always verify sensor signals and wiring integrity with an OBD2 scanner before purchasing replacement parts.
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