C009A4WD/AWD Rear Differential Unit Actuator A Position Sensor B
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- Channel B is the second of the three position signals that actuator A of the rear differential unit reports to its control module. This code points at that one line or element, while channels A and C still deliver plausible edges. A Hyundai Kefico patent explains how a controller singles out such a channel: while one healthy Hall signal keeps toggling, a channel that never changes is marked faulty and a code is stored; all three reading low hints at an open supply, all three high at a short. The same document lets the motor continue in an emergency mode by estimating rotor angle from the remaining edges. BorgWarner equips its electro-hydraulic AWD coupling with a brushless actuator whose control electronics are built in. A public C009A case from a carmaker was not found. Expect an AWD warning and a released rear clutch.
- What you may notice
- AWD warning with the vehicle driving on the front axle only
- Fault may come and go with temperature or vibration
- Likely causes
- LikelyDamaged or chafed signal wire of channel B
- PossibleLoose or spread terminal for channel B in the actuator connector
- PossibleHall element B in the actuator motor defective
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,100
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.