Powertrain, generic · Hybrid propulsion

P0BFB Drive Motor B Phase W Current Sensor Circuit Low

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P0BFB indicates that the phase W current sensor of the motor B inverter delivers a signal below its valid range. GM's limits: below -800 A on the 2011 Volt (Type A, 4 of 6 samples at 10.4 ms), below -700 A on the 2012 and 2013 two-mode trucks (Type B, two trips) and below -700 A for 0.05 of 0.1 s in the 2016 tables or 0.1 of 0.15 s in a 2019 table (Type A, one trip). The threshold lies well outside any phase current motor B can carry, so the likely cause is a sensor output stuck near ground, a failed sensor or a supply fault on the sensor board. P0BFA covers a shifted zero, P0BFC the high side. While the code is active, motor B delivers reduced or no torque.

Likely causes

Failed phase W current sensor in the motor B inverter

Sensor signal or supply pulled to ground on the sensor board

Poor contact at an internal or external inverter connector

Symptoms

Malfunction indicator lamp and hybrid warning
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: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.