What it means
The driveline control module monitors position sensor C on rear differential actuator A and sets this code when its signal indicates a sensor or circuit fault.
How it works
Position sensor C on rear differential actuator A supplies a position signal that the driveline control module uses to monitor actuator movement. C009B sets when sensor C’s signal indicates a fault or is outside the expected limits.
Common causes
Most likely first.
- Faulty actuator position sensor
- Damaged or corroded sensor connector
- Open or shorted sensor wiring
- Rear differential actuator fault
Symptoms
- AWD or 4WD warning
- AWD may be unavailable or limited
- Rear differential may not engage or disengage correctly
How to diagnose it
- Review freeze-frame and live data for actuator A position sensor C, noting whether its reading changes smoothly when actuator A is commanded.
- Inspect sensor C’s connector and its wiring at actuator A for water, corrosion, loose pins, chafing, or breaks.
- Compare the sensor C reading with actuator commands and other available position information to determine whether the signal is missing, intermittent, or implausible.
- Check sensor C’s power, ground, and signal circuits for opens or shorts, following the vehicle’s wiring information.
- If wiring is intact, assess sensor C output and actuator A movement using the manufacturer’s procedure.
- Clear the fault after repair and confirm sensor C data remains plausible during actuator operation.
Common fixes
- Clean and reseat the sensor C connector at actuator A.
- Repair damaged or corroded wiring in the sensor C circuit.
- Replace position sensor C if its output remains faulty with a verified circuit.
- Repair or replace actuator A if it sticks or cannot reach the positions the sensor is meant to report.
- Carry out the manufacturer’s calibration procedure if required after repair.
Can I keep driving?
AWD or 4WD may be unavailable or limited, and the rear differential may not engage or disengage correctly. Avoid relying on the system for extra traction until repaired, and stop if driveline behavior becomes abnormal.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.