What it means
The current sensor for drive motor B phase W 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
The phase W current sensor on drive motor B sends its measurement to the hybrid or EV control module. This code sets when that signal is below the acceptable range, often because the signal wire is shorted to ground, the sensor is internally shorted or corrosion is disrupting the connector.
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
- Capture freeze-frame data and check live phase W current or sensor readings for a low value compared with phases U and V.
- Power down the vehicle using the manufacturer’s high-voltage safety procedure, then inspect the phase W sensor connector and harness for corrosion, chafing or pinched wires.
- Check connector terminal condition and verify the phase W signal, power and ground circuits against the manufacturer’s specification.
- Test the phase W signal wire for a short to ground and check sensor output using the manufacturer’s circuit test.
- If wiring and terminals are sound, test the phase W sensor and module input to locate the fault.
Common fixes
- Clean corroded phase W connector terminals and restore secure contact.
- Repair phase W signal wiring that is shorted to ground or damaged.
- Repair a faulty phase W sensor power or ground connection identified during testing.
- Replace the phase W current sensor if its output remains low with a sound circuit.
- Repair or replace a control module only if its input is confirmed faulty.
Can I keep driving?
A low phase W signal can cause reduced torque, limp mode or a vehicle shutdown. Avoid driving if power is reduced or unstable, because the vehicle may lose propulsion.
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.