Powertrain, generic · Hybrid propulsion

P0BF9 Drive Motor B Phase W Current Sensor Circuit

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P0BF9 is reserved for a general circuit fault of the phase W current sensor in the drive motor B inverter, outside the offset, low and high categories that have their own codes. No manufacturer documents this exact code publicly; GM's tables from the 2011 Volt through 2019, and Jeep's 2020 Renegade and Compass PHEV bulletins, refer only to the specific siblings, chiefly P0BFA. CARB requires hybrid sensor circuits to be monitored. If the controller cannot trust phase W of motor B, it can no longer close the three-phase current balance checked by P0BFE and therefore limits or disables that motor. The sensor sits inside the inverter, so repair usually means replacing the inverter assembly.

Likely causes

Failed phase W current sensor in the motor B inverter

Supply or signal fault on the inverter's sensor board

Software fault in the motor B control processor

Symptoms

Hybrid system warning and malfunction indicator lamp
Reduced power or no contribution from drive motor B

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€150–4,000

Time1–6 h

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

Parts involved

drive motor b phase w current sensorwiring harnesshybrid control module

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