What Does P0B06 Mean?
The powertrain control module has detected a general electrical fault in the Phase W motor winding circuit of the auxiliary transmission fluid pump. This is the third phase of the three-phase motor, and a fault here will prevent balanced motor operation. The pump may fail to start, run with severe vibration, or produce insufficient fluid flow for proper transmission operation during hybrid engine-off modes.
Common Causes
35%
Failed Phase W motor winding (open or shorted internally)
25%
Corroded or damaged wiring in the Phase W circuit
20%
Poor connector contact at the pump motor or control module
15%
Control module Phase W driver circuit internal failure
5%
Wiring harness chafe or damage from vibration or routing interference
Diagnostic Steps
1
Read freeze frame data to understand the operating conditions when the fault occurred. Note engine state, transmission temperature, and hybrid mode.
2
Disconnect the pump motor and measure all three winding resistances (U, V, W). Phase W should match the other two within 10%. An open reading or significantly different resistance confirms a Phase W winding fault.
3
Measure insulation resistance from Phase W to motor case ground and between Phase W and the other two phases. Values below 10K ohms indicate a short circuit.
4
Inspect the complete Phase W wiring path from the control module to the motor. Look for chafing, cuts, heat damage, or pinch points where the harness passes through brackets or near hot exhaust components.
5
Command pump operation via the scan tool and monitor Phase W current compared to the other phases. Absent current confirms an open; excessive current confirms a short.
Estimated Repair Cost
$300 - $1,800
Parts + labor, varies by vehicle and location
The powertrain control module has detected a general electrical fault in the Phase W motor winding circuit of the auxiliary transmission fluid pump. This is the third phase of the three-phase motor, and a fault here will prevent balanced motor operation. The pump may fail to start, run with severe v...
The most common cause of P0B06 (Auxiliary Transmission Fluid Pump Motor Phase W Current) is: Failed Phase W motor winding (open or shorted internally)
Typical repair costs for P0B06 range from $300 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Without Phase W, the three-phase pump motor cannot operate properly. The vehicle will disable auto-stop and EV drive modes. Engine-on driving is safe, but continued operation without the auxiliary pump during engine-off conditions risks inadequate transmission lubrication. Schedule repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0B06 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid Transmission Auxiliary Systems
Difficulty
Type
Generic (SAE)
Recommended Tools
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