What it means
Drive motor B phase U current is above the expected range. The code identifies a high-current condition but does not establish its cause.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The inverter switches current through drive motor B’s phase U winding to make torque. The module monitors phase U current and sets this code when it rises above the expected range; a short between motor phases or a stalled rotor can cause excessive current.
Common causes
Most likely first.
- Short between motor phases
- Rotor stalled - high stall current
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 U current with phases V and W, checking whether phase U is unusually high or unbalanced.
- Review related motor B, inverter, and rotor-speed codes for evidence of a phase short or a motor that is not turning.
- With the vehicle safely powered down according to the manufacturer’s procedure, inspect motor B phase wiring for damaged insulation, melted sections, or conductors touching each other.
- Have the motor B windings and insulation tested for a phase-to-phase short using the manufacturer’s procedure.
- If the motor and wiring pass, have the rotor and inverter checked for a stall or a fault that could drive excessive phase U current.
Common fixes
- Repair chafed or damaged phase wiring and restore insulation between conductors.
- Repair a damaged motor B phase U connector.
- Repair or replace the motor if a phase-to-phase short or rotor seizure is confirmed.
- Repair or replace the inverter if testing confirms it is causing excessive phase U current.
Can I keep driving?
Do not continue driving if there is reduced torque, abnormal motor noise, limp mode, or a shutdown warning; propulsion may be lost suddenly and the high current can damage the motor or inverter further. Arrange prompt hybrid-system diagnosis.
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.