P0504: Brake Switch A / B Correlation
What does P0504 mean?
P0504 is a diagnostic trouble code indicating "Brake Switch A / B Correlation". This code relates to your vehicle's braking system and should be diagnosed to determine the root cause. The severity level helps indicate how urgently this should be addressed.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- ABS warning light on
- Brake pedal feels different
- Unusual braking behaviour
Estimated repair cost
Typical range in Australia (parts + labour)
Common causes
- Faulty braking system component
- Wiring or connector issue in the related circuit
- Failed sensor providing incorrect readings
- Software/calibration issue requiring ECU update
- Related component causing secondary fault
What should you do?
This code sits in the braking system. Your normal hydraulic brakes generally still work, but the electronics layered on top of them, ABS, EBD and emergency brake assist, can drop out. You will not notice until you brake hard or brake on a wet or loose surface, and that is the moment they would have helped. Treat the car as needing a workshop rather than as safe to drive, and get it looked at before your next real trip.
Get a diagnosis for YOUR car
Code P0504 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.