What it means
The control module detected a fault associated with drive motor B phase W current. The code alone does not identify whether the cause is in the current measurement circuit, inverter, or motor.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Drive motor B phase W is one of the inverter-controlled current paths that produce torque. The module monitors phase W current and sets this code when it detects a related fault, but the code does not identify whether the sensor, wiring, inverter, or motor is responsible.
Common causes
Most likely first.
- Phase 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
- Save freeze-frame data and compare live motor B phase W current with phases U and V under the conditions that set the code.
- Check for related motor B, inverter, or current-sensor codes that may help narrow the source.
- With the vehicle safely powered down according to the manufacturer’s procedure, inspect motor B phase W wiring and connectors for corrosion, loose pins, heat damage, or chafing.
- Test the phase W current-sensor supply, ground, and signal circuit for continuity and shorts using the manufacturer’s wiring information.
- If the wiring passes, test the phase W current sensor against the manufacturer’s specification, then investigate the inverter or motor if the sensor is sound.
Common fixes
- Clean and secure a loose or corroded motor B phase W connector.
- Repair damaged phase W wiring or its sensor signal circuit.
- Replace the phase W current sensor if it fails testing.
- Repair the inverter or motor only if further tests isolate the fault to that component.
Can I keep driving?
Limit driving if motor power is reduced and stop safely if limp mode or a shutdown warning appears, since the vehicle may lose propulsion. Arrange prompt diagnosis of the phase W current fault.
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.