What it means
The phase currents of the clutch B BLDC motor do not match the commanded commutation pattern within tolerance. Sensor or driver synchronisation off.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The clutch B brushless motor controller switches current through U, V and W in a timed pattern, using rotor position to keep the motor synchronized. The transmission control module sets this code when measured phase behavior does not match the commanded commutation pattern closely enough, indicating a phase-current imbalance or position/timing mismatch.
Common causes
Most likely first.
- Rotor position sensor offset
- Phase current imbalance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and review clutch B motor command, rotor position and phase-current data to see whether the mismatch appears at a particular speed or load.
- Inspect the clutch B motor connector and U, V and W wiring for corrosion, loose terminals, damaged insulation or routing near a source of electrical interference.
- Check the rotor-position sensor connector and wiring for poor contact or damage that could shift or disturb the position signal.
- Compare clutch B rotor-position and phase-current readings during the manufacturer's specified scan-tool test to identify which signal loses synchronization.
- Test phase wiring and motor windings for continuity and balance against the manufacturer's specification before concluding the sensor or motor is faulty.
Common fixes
- Repair loose, corroded or damaged clutch B phase wiring and connections.
- Repair or reroute damaged rotor-position sensor wiring causing signal interference.
- Correct a rotor-position sensor alignment issue using the manufacturer's procedure.
- Replace the failed position sensor or clutch B motor if testing confirms the component is outside specification.
Can I keep driving?
Limit driving and avoid heavy acceleration or repeated shifts, since clutch B may engage unevenly and cause shudder, slipping or sudden changes in gear. If the transmission enters limp mode or the symptoms worsen, stop driving and arrange repair.
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.