Powertrain, generic · Hybrid propulsion

P0B01 Electric/Auxiliary Transmission Fluid Pump Motor Phase U Current Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Pump motor connector not fully seated or latched (Chevrolet Spark EV)
Open circuit in the phase U lead or terminal of the pump motor cable
Phase U switch in the pump inverter not conducting
Open winding of phase U in the pump motor

Symptoms

  • Service Vehicle Soon light and MIL
  • Propulsion Power Reduced or Vehicle Speed Limited message

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time1–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

aux trans pump motor phase uaux trans pump control modulewiring harness

Related codes

P0B00P0B02P0B04P0B07P0C20P0C27

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.