Powertrain, generic · Hybrid propulsion

P0B07 Electric/Auxiliary Transmission Fluid Pump Motor Phase W Current Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B07 means phase W of the auxiliary fluid pump motor carries less current than commanded, the typical sign of an open W path. GM uses it on the Volt and later hybrids: below 1 A peak W-axis current for 0.4 s of 0.6 s, with the inverter in normal PWM above 50 V, sets a Type A fault. A GM service update for the 2017-18 Cadillac CT6 plug-in shows the code had been calibrated off; a W phase loss then shut the car down or prevented starting with no code and no MIL, until reprogramming of the drive motor power inverter module enabled P0B07 as Type A. On the 2014-15 Spark EV, bulletin PI1433 ties P0B01, P0B04 or P0B07 to an unlatched pump connector. P0B01 and P0B04 are phases U and V, P0B08 the high side, P0B06 the general W code.

Likely causes

Pump motor connector not fully seated or latched (Chevrolet Spark EV)
Open circuit in the phase W lead or terminal
Outdated inverter software (Cadillac CT6 plug-in, service update 18199)
Open winding of phase W in the pump motor

Symptoms

  • MIL and Service Vehicle Soon light
  • Loss of propulsion, vehicle shutdown or no-start

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–2,500
Time0.5–6 h

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

Parts involved

aux trans pump motor phase waux trans pump control modulewiring harness

Related codes

P0B01P0B04P0B06P0B08P0C27P0C28

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