C05AFBrake Booster Motor B Current Sensor Circuit Range/Performance
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C05AF is the plausibility check of the current measurement on booster side B, the second motor or winding system. No manufacturer publishes it. A separate sensing chain for B is needed wherever each power module controls its own winding, as in the Hyundai Mobis dual-winding booster motor, since every module must know its phase currents to regulate torque and to judge its own health. Typical checks run at start-up, before current flows: the controller shorts the amplifier inputs (TI's DRV8343-Q1 offers a pin for this), records the zero point and rejects values outside a band. GM's counterpart for side A, C0596, additionally injects test offsets. A failed B measurement normally leads to side B being switched off and assist relying on side A, possibly with lower power.
- What you may notice
- Brake assist or brake system warning
- Possibly weaker assist under hard braking
- Likely causes
- PossibleFaulty current sense amplifier of side B
- PossibleZero offset of side B outside its allowed band
- RareDamaged shunt or solder joint in power module B
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €200 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.