What it means
The current sensor for drive motor B phase U reports a circuit high 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 inverter monitors current in drive motor B’s U phase through a dedicated current sensor. This code sets when the phase U sensor circuit produces an abnormally high signal, making that phase’s current reading unreliable.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- 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
- Save freeze-frame data and inspect live drive motor B phase U current readings to confirm when the high signal occurs and check for related inverter codes.
- With the high-voltage system made safe according to the manufacturer's procedure, inspect the phase U sensor connector and harness for damage, corrosion, loose pins, or a signal wire shorted to B+.
- Test the phase U signal, supply, and ground circuits for shorts to B+, opens, or poor contact using the manufacturer's wiring information.
- Compare drive motor B phase U readings with phases V and W under the same conditions to see if the high reading is isolated to U.
- If wiring checks pass, test the drive motor B phase U current sensor using the manufacturer's diagnostic procedure.
Common fixes
- Clean and secure the phase U sensor connector terminals.
- Repair a phase U signal wire shorted to B+ or damaged harness.
- Correct a poor sensor supply or ground connection.
- Replace the drive motor B phase U current sensor if its output remains high with sound wiring.
Can I keep driving?
Do not keep driving if the vehicle has reduced torque, entered limp mode, or warns of possible shutdown; loss of drive may occur. Avoid high-demand use until the phase U circuit fault is addressed.
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.