P0B05 code meaning
Electric/Auxiliary Transmission Fluid Pump Motor Phase V Current High
Powertrain system Generic code P0Bxx codes Check engine light
What P0B05 means
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.
P0B05 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0B05
- MIL and transmission or hybrid warning
- Loss of propulsion or no-start in severe cases
Common causes of P0B05
- Most 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
- Less likelyShorted turns in phase V of the pump motor
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aux trans pump motor phase vAux trans pump control moduleWiring harness
What each part of P0B05 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B | Area: hybrid propulsion. |
| 05 | The exact fault in that area. |
What to do next
- Note P0B05 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0B05
What does P0B05 mean?
P0B05 means "Electric/Auxiliary Transmission Fluid Pump Motor Phase V Current High". P0B05 flags overcurrent in phase V of the electric auxiliary transmission fluid pump motor. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B05?
Drive gently and only to a workshop. With P0B05 the car can go into limp mode (reduced power) to protect itself.
Will P0B05 fail an emissions test?
Yes, it can. P0B05 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0B05 to fix?
Difficulty: hard. A typical repair takes 0.5 to 6 hours of work. This is a job for a workshop.
Will P0B05 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.