What it means
The phase U, V, and W current sensors of drive motor B do not correlate within the calibrated tolerance. Sum of phase currents should be near zero.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Drive motor B’s U, V and W current sensors each report one phase to the hybrid or EV control module. This code sets when their readings fail to balance within the expected tolerance, often because one sensor has drifted or the sensors have a ground offset.
Common causes
Most likely first.
- One sensor offset drifted
- Ground offset between sensors
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Capture freeze-frame data and compare live motor B U, V and W phase current readings to see which phase appears out of balance.
- Using the manufacturer’s high-voltage shutdown procedure, inspect the motor B phase sensor connectors and shared grounds for damage, looseness or contamination.
- Check the phase sensor grounds and connector contacts for poor connections or ground offset, comparing them with the manufacturer’s specification.
- Compare each motor B sensor output under the manufacturer’s specified conditions to identify a drifting sensor.
- If the circuits and grounds are sound, test the three sensors and control module inputs according to the manufacturer’s procedure.
Common fixes
- Clean and secure the affected motor B phase sensor connector or ground connection.
- Repair damaged wiring or ground connections serving the motor B phase sensors.
- Replace the motor B phase current sensor confirmed to have drifted.
- Repair or replace the control module only if its inputs or processing are confirmed faulty.
Can I keep driving?
The vehicle may reduce torque, enter limp mode or shut down when motor B phase readings do not agree. Avoid driving with reduced or unstable power because propulsion could be lost.
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.