C009E4WD/AWD Rear Differential Unit Actuator B Position Sensor B
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- Middle channel B of the second rear-unit actuator is reported here. It belongs to designs with two independently controlled elements; GKN's Twinster, used on the Focus RS rear drive module, can send torque to either rear wheel separately through two wet clutches. A fault in channel B of actuator B is typically an interrupted, grounded or frozen signal while channels A and C still switch. The detection logic in a Hyundai Kefico patent fits this case: it takes a healthy channel as reference, and a partner that never changes while the reference toggles is stored as defective. That patent also lets the motor run on in an emergency mode from the remaining edges. No public manufacturer document names C009E. The usual result is that the controller stops using the affected side and shows an AWD warning.
- What you may notice
- AWD fault message, one rear wheel no longer driven actively
- Drift or sport drive modes unavailable
- Likely causes
- LikelyChannel B signal of actuator B interrupted or grounded
- PossibleHarness chafed near the rear axle or exhaust heat shield
- PossibleInternal sensor failure in actuator B
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.