P0BFB: Drive Motor B Phase W Current Sensor Circuit Low

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.

Symptoms

• Malfunction indicator lamp and hybrid warning
• Reduced power or no contribution from drive motor B

Most 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

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. Leave any high-voltage measurements to a specialized repair shop

Good to know

• It can trigger limp mode.
• It affects emissions.

What each character of P0BFB means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• B: Subsystem depends on the code range
• FB: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0BFB?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0BFB?

The most common causes are: 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.

Related codes

• P0BFCDrive Motor B Phase W Current Sensor Circuit High
• P0BF9Drive Motor B Phase W Current Sensor Circuit
• P0BFADrive Motor B Phase W Current Sensor Circuit Range/Performance
• P0BF3Drive Motor B Phase U Current Sensor Circuit Low
• P0BF7Drive Motor B Phase V Current Sensor Circuit Low
• P0BEFDrive Motor A Phase W Current Sensor Circuit Low
• P0BFEDrive Motor B Phase U-V-W Current Sensor Correlation

Sources

• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 16OBDG02 Hybrid Diagnostics
• gsi.ext.gm.com: 11OBDG01 HYBRID Diagnostics
• gsi.ext.gm.com: 13OBDG06 Hybrid Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.