P0504 on Hyundai Sonata
Brake Switch A/B Correlation
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Hyundai Sonata context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0504.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0504 Means on Your Hyundai Sonata
P0504 is a diagnostic trouble code indicating: Brake Switch A/B Correlation. This code relates to the vehicle speed and idle control system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Hyundai Sonata Owner Reports
Source: NHTSA Complaints Database
"Campaign #092 was replaced on my vehicle at bel air hyundai on 9/14/2010. the vehicle was there for other regular service and the recall was performed. at that time, the switch was not a problem. no check engine light and we were unaware that this recall was even performed."
"My brake lights no longer function. my "esc off" light and check engine light appeared. i had a mechanic scan my car regarding the aforementioned issues and the code that displayed was "p0504"."
"I drive a 2012 Hyundai Sonata Limited. After a recent fill-up, I began experiencing delayed acceleration, engine hesitation, and what appears to be misfiring—especially at low throttle."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Hyundai Sonata
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.