P0B05Electric/Auxiliary Transmission Fluid Pump Motor Phase V Current High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0B05 flags overcurrent in phase V of the electric auxiliary transmission fluid pump motor. No manufacturer publicly documents this specific code. GM monitors the same physical fault without naming the phase: P0C28 trips when any of U, V or W exceeds 35 A for about 10 ms within a 62 ms window, and a 2018 Cadillac CT6 plug-in service update shows how a faulty pump restart routine alone can push the current over that limit. Likely triggers for a V-specific high code are a short in the V lead, shorted turns, a seized or contaminated pump, or a restart against a stalled rotor. The Hitachi patent on sub-oil pump drives shows the phase currents come from a shared sensor. Auto-stop is usually blocked. P0B04 is the low side, P0B02 and P0B08 phases U and W.
- What you may notice
- MIL and transmission or hybrid warning
- Loss of propulsion or no-start in severe cases
- Likely causes
- LikelyPhase V lead shorted to another phase or to ground
- PossiblePump seized or contaminated, motor draws excess current
- PossiblePump restart logic in the inverter software causing overcurrent
- RareShorted turns in phase V of the pump motor
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.