P0BF4Drive Motor B Phase U Current Sensor Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0BF4 is the upper-limit counterpart of P0BF3 for the phase U current sensor of drive motor B. GM's thresholds: above 800 A on the 2011 Volt, checked with PWM output disabled (Type A); above 700 A on the 2012 and 2013 two-mode trucks (Type B, two trips); above 700 A for 0.05 of 0.1 s in the 2016 tables and 0.1 of 0.15 s in a 2019 table (Type A, one trip). Because the test runs with the power stage idle or the value lies far beyond any real current, it points to the sensor, its supply or an open reference rather than to genuine overcurrent; GM reports real excess phase current of motor B separately under P0C04 (above 600 A in the 2016 and 2019 tables). Motor B output is limited until repair.
- What you may notice
- Malfunction indicator lamp and hybrid warning
- Reduced power from drive motor B
- Further inverter or phase current codes stored
- Likely causes
- LikelyFailed phase U current sensor in the motor B inverter
- PossibleSensor signal shorted to the sensor supply voltage or open reference ground
- RarePoor contact at an internal or external inverter connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.