C0504Left Front Wheel Speed Sensor A Intermittent/Erratic
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- C0504 points to a left front speed signal that jumps or produces far too many edges, not one that is missing. GM's 2016 hybrid brake module stores a time stamp for every sensor edge in a buffer and sets C0504 within 0.03 s when that buffer overflows; the 2023 tables apply the same idea to a DMA transfer unit receiving time stamps too often. For 2020 Chevrolet Silverado and GMC Sierra 2500/3500HD, GM preliminary information PIT5707 ties C0504 and its right-hand twin C050A to manufacturing debris on the reluctor ring: clean it without using a magnet, which may mean removing the hub bearing. Mitsubishi (C1061-38) checks the signal between 10 and 60 km/h, needs two trips for the MIL and lists the sensor rotor among the causes.
- What you may notice
- ABS lamp and service stability message on the driver display
- Fault comes and goes with road surface or steering angle
- Likely causes
- LikelyMetal debris or dirt on the reluctor ring (GM PIT5707)
- PossibleLoose contact in the sensor plug or a wire breaking under movement
- PossibleDamaged tone ring or encoder
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.