What it means
The current sensor for drive motor B phase U reports a circuit 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
Drive motor B is controlled by an inverter that manages current in its U, V, and W phases. The control module monitors the drive motor B phase U current sensor circuit; this code sets when that circuit has a fault and its current reading cannot be trusted.
Common causes
Most likely first.
- Current sensor failed
- Wiring fault
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 review live drive motor B phase U current sensor readings and related inverter codes to determine when the circuit fault occurs.
- With the high-voltage system made safe according to the manufacturer's procedure, inspect the drive motor B phase U sensor connector and harness for damage, corrosion, loose pins, or chafing.
- Check the phase U sensor signal, supply, and ground circuits for opens, shorts, or poor connections using the manufacturer's wiring information.
- Compare drive motor B phase U readings with its phases V and W under comparable conditions to see whether the fault is confined to U.
- If wiring and connections pass inspection, test the drive motor B phase U current sensor using the manufacturer's diagnostic procedure.
Common fixes
- Clean and secure a loose or corroded phase U sensor connector.
- Repair damaged or open wiring in the drive motor B phase U sensor circuit.
- Correct a short or poor supply or ground connection in that circuit.
- Replace the drive motor B phase U current sensor if it fails testing with sound wiring.
Can I keep driving?
Reduced torque or limp mode can impair acceleration and may precede a vehicle shutdown, so avoid driving if those symptoms occur. Do not rely on the vehicle for a trip where sudden loss of drive would be hazardous.
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.