What it means
The current sensor for drive motor B phase U reports a circuit low fault. Phase current measurement is unreliable.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
A current sensor in the inverter measures current through drive motor B’s U phase. This code sets when the phase U sensor signal is abnormally low, preventing the control module from accurately monitoring that phase.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Record freeze-frame data and check live drive motor B phase U sensor readings alongside related inverter codes to confirm the low signal.
- With the high-voltage system made safe according to the manufacturer's procedure, inspect the phase U sensor connector and harness for corrosion, loose terminals, damage, or a signal wire shorted to ground.
- Use the manufacturer's wiring information to check the phase U signal, supply, and ground circuits for shorts to ground, opens, or excessive connection resistance.
- Compare drive motor B phase U readings with phases V and W under equivalent conditions to identify whether only the U circuit is affected.
- If the circuit is sound, test the drive motor B phase U current sensor for an internal short or failed output according to the manufacturer's procedure.
Common fixes
- Clean and secure corroded or loose phase U connector terminals.
- Repair a phase U signal wire shorted to ground or damaged harness section.
- Restore a poor sensor supply or ground connection.
- Replace the drive motor B phase U current sensor if it still reads low with a verified circuit.
Can I keep driving?
If the vehicle is in limp mode or has reduced power, avoid driving in traffic or on routes where a sudden loss of drive would be dangerous. Stop safely if a shutdown warning appears.
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.