P0B01 code meaning
Electric/Auxiliary Transmission Fluid Pump Motor Phase U Current Low
Powertrain system Generic code P0Bxx codes Check engine light
What P0B01 means
P0B01 means the pump inverter sees almost no current in phase U of the auxiliary fluid pump motor, typically an open phase. GM documents the check for the Volt motor control processor (2016) and its hybrid tables of 2018 and 2019: with the drive state in Run, the inverter in normal PWM above 50 V and a squared current command above 5 A2 (2016) or 14.97 A2 (2018), the peak current on the U axis is compared while the rotor is within 30 degrees of it; below 1 A for 0.4 s of a 0.6 s window, the code sets as Type A, MIL on the first trip. On the 2014-15 Chevrolet Spark EV, GM bulletin PI1433 links P0B01, P0B04 or P0B07, Service Vehicle Soon and reduced propulsion to an unlatched pump connector. P0B04/P0B07 are phases V and W, P0B02 the high side.
P0B01 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0B01
- Service Vehicle Soon light and MIL
- Propulsion Power Reduced or Vehicle Speed Limited message
Common causes of P0B01
- Most likelyPump motor connector not fully seated or latched (Chevrolet Spark EV)
- PossibleOpen circuit in the phase U lead or terminal of the pump motor cable
- PossiblePhase U switch in the pump inverter not conducting
- Less likelyOpen winding of phase U in 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 uAux trans pump control moduleWiring harness
What each part of P0B01 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. |
| 01 | The exact fault in that area. |
What to do next
- Note P0B01 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 P0B01
What does P0B01 mean?
P0B01 means "Electric/Auxiliary Transmission Fluid Pump Motor Phase U Current Low". P0B01 means the pump inverter sees almost no current in phase U of the auxiliary fluid pump motor, typically an open phase. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B01?
Drive gently and only to a workshop. With P0B01 the car can go into limp mode (reduced power) to protect itself.
Will P0B01 fail an emissions test?
Yes, it can. P0B01 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 P0B01 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0B01 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.