C0502Left Front Wheel Speed Sensor A Circuit Low
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- C0502 reports the left front sensor circuit below its valid level, mostly a grounded wire or a supply that has sagged. In GM's 2019 tables (19OBDG03D) the brake module's Polaris ASIC sets C0502 for three conditions: the low side shorted to ground, tested only at power-up or after clearing codes (100 ms); sensor undervoltage (20 ms); and, unusually, an open sensor drawing under 3.5 mA, which other GM tables file as C0500. All are Type A. Audi bulletin 2061331/1 for 2017–2021 A4, A5, S and RS models stores C050200 as short to ground: a wire was poorly crimped in the front sensor connector, and the remedy is a new speed sensor and pad-wear harness. Mitsubishi's C1061-11 covers short and open circuits and even lights the parking brake warning.
- What you may notice
- ABS and ESC lamps on right after starting
- Parking brake warning or electric parking brake functions restricted on some models
- Likely causes
- LikelySensor wire chafed through to ground or poorly crimped in the connector
- PossibleSensor supply voltage too low (battery, fuse or module output)
- RareInternal short in the left front sensor
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.