What it means
The control module detects phase U current above the expected level in the electric/auxiliary transmission fluid pump motor.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Phase U is one of the three phases powering the electric or auxiliary transmission-fluid pump motor. P0B02 sets when the control module detects phase-U current above the expected level, which can indicate a shorted winding or wire, a binding pump, or an erroneous current reading.
Common causes
Most likely first.
- Shorted phase wiring or motor winding
- Pump motor binding or stalled
- Current sensing or control fault
Symptoms
- Transmission or hybrid system warning light
- Transmission operation may be limited
How to diagnose it
- Review freeze-frame data and related pump codes to determine whether high phase-U current occurred with a pump command or transmission warning.
- Compare live phase-U current with phases V and W during the specified pump operation to confirm the high reading is isolated to phase U.
- Inspect phase-U wiring and the pump connector for pinched insulation, shorts, melted areas, or terminal damage.
- With the system made safe according to service information, test phase-U wiring for shorts and check the pump motor for binding or abnormal mechanical resistance.
- If wiring and pump movement are sound, test the motor windings and current-sensing or control circuit against the manufacturer's specifications.
Common fixes
- Repair pinched or shorted phase-U wiring and replace damaged connector terminals.
- Replace the pump motor if a shorted phase-U winding or binding motor is confirmed.
- Repair the current-sensing circuit if its reading is inaccurate.
- Repair the pump control circuit if testing identifies an incorrect drive condition.
Can I keep driving?
Avoid continued driving if the transmission warning is accompanied by limited operation, unusual shifting, or limp mode; an overloaded pump can fail and fluid circulation may be affected. Stop safely if the transmission behaves abnormally.
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.