P0504 — Brake switch A / B correlation

Code P0504 is a standard OBD-II diagnostic trouble code: Brake switch A / B correlation.

In our record, P0504 is reported most often on Hyundai, Kia and Ford vehicles , against brakes and electrical failure patterns , across 2006–2017 model years. Hyundai alone accounts for 75% of them.

In ProblemsByVin's analysis of the NHTSA owner-complaint record, owners cite P0504 across 8 vehicle failure patterns. Diagnostic codes in complaints are reported by owners and are unverified — they point to where this code shows up, not a confirmed diagnosis. Open a page below for the full pattern (symptoms, mileage, repair costs owners cite).

Vehicles where owners report P0504 8 patterns

2017 Kia Forte

powertrain — Total loss of electrical power while driving

2015 Ford Mustang

brakes — Brake pedal stop pad/bumper fracture

2012 Hyundai Sonata

electrical — Brake Light Switch Malfunction

2007 Hyundai Santa Fe

brakes — Brake light switch failure—lights remain on or do not illuminate

2007 Hyundai Sonata

electrical — Brake Light / Brake Switch Circuit Fault

2007 Hyundai Santa Fe

lighting — Brake light switch failure

2006 Hyundai Sonata

brakes — Stop lamp switch failure (recalled multiple times, recurring defect)

2006 Hyundai Sonata

lighting — Brake light switch failure / stop lamp malfunction

Codes are pulled from what owners wrote in their NHTSA filings — they're allegations, not a shop diagnosis. Always confirm with a live scan. Browse all diagnostic codes →