P0504: owner reports and bulletins
Got P0504 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.
What owners report to NHTSA
9 complaints filed with NHTSA mention P0504, 4 of them since 2015, across 4 different models. The component owners most often filed it under: service brakes.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| HYUNDAI SONATA | 4 | 2006, 2007, 2012 |
| HYUNDAI SANTA FE | 3 | 2007 |
Manufacturer service bulletins that name P0504
14 technical service bulletins and manufacturer communications filed with NHTSA mention P0504, from 4 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- MAZDA CX-90 (2024), bulletin 10244568: Some customers may experience a "Push Button Start Malfunction. Have the Vehicle Inspected" warning message and the following DTC(s) may be stored. C0040:24 - Brake switch (No.1 signal) circuit malfunction P0504:00 - Bra…
- FORD F-450 SD (2020, 2021, 2022), bulletin 10208141: Some 2020-2022 F-Super Duty vehicles may exhibit a condition where the engine will not turn off and/or have various electrical symptoms including a dead battery, horn stays on and no crank/no start. The vehicle may also …
- FORD F-250 SD (2020, 2021, 2022), bulletin 10214495: Some 2020-2022 F-Super Duty vehicles may exhibit a condition where the vehicle will not shift out of park (P). Diagnostic trouble codes (DTC) C0040 and/or P0504 may also be present. Reference TSB 22-2044 to make sure tha…
- FORD ESCAPE (2020, 2021), bulletin 10202798: Some 2020-2021 Escape vehicles may exhibit various symptoms due to a loss of voltage reference (VREF) from the 14290 harness above the steering shaft u-joint. Possible symptoms may include an illuminated malfunction indi…
- FORD ECOSPORT (2021), bulletin 10203717: Some 2021 EcoSport vehicles equipped with a 1.0L EcoBoost engine may exhibit a condition where the auto start/stop system is inoperative or cruise control disabled with an illuminated powertrain malfunction (wrench) and/…
- HONDA CRF1100L (2020, 2021, 2018, 2019), bulletin 10213581: "Newsletter - If the LCD screen is blank/inoperative and asterisks appear in place of the riding modes, perform the following test. Inspect the number five (15 amp) audio fuse next to the battery in the main fuse box. If…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.