C05A3Wheel Speed Sensors Supply Circuit High
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- Active wheel speed sensors are fed by the ABS module and send their pulses back as a current on the same pair of wires, as HELLA explains. C05A3 reports that this common supply is too high or cannot be switched off. GM's 2016 and 2019 hybrid brake controllers look for reverse current on the supply line, the sign of a short to the battery feed, for over 3.5 s. A 2019 GM EBCM with a system ASIC uses C05A3 for two cases: the sensor supply exceeds its overvoltage limit, after which the ASIC turns off all four high-side switches, and a periodic test in which a supposedly switched-off high side is still live. Both are Type A with MIL. Allegro rates its wheel speed sensor IC for 24 V and clamps at 28 V. With no wheel speeds, ABS, ESC and traction control stop working.
- What you may notice
- ABS, traction and stability control warning lamps on at the same time
- Several or all wheel speed signals lost, speedometer may drop out
- MIL on (GM)
- Likely causes
- LikelyWheel speed sensor wire chafed and shorted to battery voltage
- PossibleSupply switch or ASIC in the brake module stuck on
- RareWater in a wheel speed sensor connector bridging to a powered circuit
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.