Powertrain, generic · Hybrid propulsion

P0B06 Electric/Auxiliary Transmission Fluid Pump Motor Phase W Current

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B06 is the general current fault for phase W of the auxiliary transmission fluid pump motor. No manufacturer publishes a monitor description for this exact code. GM covers phase W in its Volt, ELR and CT6 calibrations with the low-side code P0B07 and treats overcurrent on any phase as P0C28. CARB requires hybrid and transmission components whose failure affects emissions or other monitors to be checked for circuit faults and rationality, which is why manufacturers can use the general code for implausible readings. The Hitachi sub-oil pump patent describes a sinusoidal drive whose W current is calculated from a single bus shunt, so wiring, sensing and the power stage are all suspects. The pump stops and auto-stop is blocked. P0B07/P0B08 are the low and high variants, P0B00 and P0B03 phases U and V.

Likely causes

Poor contact in the phase W lead or pump connector
Current sensing in the pump inverter faulty
Phase W power stage in the pump control module faulty
Winding fault in phase W of the pump motor

Symptoms

  • MIL or transmission/hybrid warning
  • Engine keeps running at stops, no auto-stop

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time1–6 h

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

Parts involved

aux trans pump motor phase waux trans pump control modulewiring harness

Related codes

P0B00P0B03P0B07P0B08P0C20P0C28

References: law.cornell.edu, patents.google.com, gsi.ext.gm.com.