Diagnostic trouble code C0504 indicates: Izquierdo Delantero Rueda Velocidad Sensor A Intermitente/Errático. It was set by your vehicle's onboard diagnostics system and will typically keep the check engine light on until it's addressed.
Upload your ECU file and DTC Doctor will detect this code (and any others) automatically, then remove it for good — no dealer visit, no guesswork.
Analyze My File Free →