P0504
Brake Switch \"A\"/\"B\" Correlation
Modern vehicles use two redundant brake switch signals (often one normally-open and one normally-closed). When the two signals disagree, this code is set; common causes include a misadjusted switch, internal switch failure, or wiring fault.
Modern vehicles use two redundant brake switch signals (often one normally-open and one normally-closed). When the two signals disagree, this code is set; common causes include a misadjusted switch, internal switch failure, or wiring fault.
Common causes
- high
Brake switch misadjusted
One of the most commonly reported causes for this code — check this first.
Typical part cost: $30-220
- medium
Brake switch internal fault
A plausible cause — test and verify before replacing parts.
Typical part cost: $30-220
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P0504 mean?
P0504 means "Brake Switch \"A\"/\"B\" Correlation". It is a generic OBD-II code that points to a fault in the vehicle speed, idle control, auxiliary inputs.
What are the most common causes of P0504?
brake switch misadjusted; brake switch internal fault — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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