Powertrain, generic · Hybrid propulsion

P0BF1 Drive Motor B Phase U Current Sensor Circuit

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

On hybrids with two electric machines, the inverter of drive motor B carries its own set of phase current sensors, which the motor control processor uses for torque control and to protect the power switches. P0BF1 is the general circuit code for the phase U sensor of motor B, meant for an electrical fault that is not classified as offset, low or high. No manufacturer documents this exact code publicly: GM's tables for the 2011 Volt, the 2012 and 2013 two-mode trucks and the 2016 to 2019 models list only P0BF2, P0BF3 and P0BF4 for this sensor. CARB requires hybrid sensor circuits to be monitored. Without a valid phase U value, motor B is usually limited or switched off.

Likely causes

Failed phase U 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
Engine runs more often because electric drive is limited

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 u current sensorwiring harnesshybrid control module

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