P0BF7: Drive Motor B Phase V Current Sensor Circuit Low

What it means

The current sensor for drive motor B phase V reports a circuit low fault. Phase current measurement is unreliable.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Drive motor B’s phase V current sensor reports current in that motor phase to the hybrid or EV control module. This code sets when the phase V signal is lower than the module’s acceptable range, which can result from a signal short to ground, a failed sensor or a poor connector connection.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Internal sensor short
3. Connector pins corroded - high contact resistance

Symptoms

• EV/hybrid system warning light on
• Reduced motor power or torque
• Possible limp mode or vehicle shutdown

How to diagnose it

1. Record freeze-frame data and check live phase V current or sensor data for a reading pinned low compared with phases U and W.
2. With the vehicle safely powered down using the manufacturer’s high-voltage procedure, inspect the phase V sensor connector and harness for corrosion, chafing or a short to ground.
3. Check connector terminal fit and corrosion, then verify phase V sensor power, ground and signal wiring against the manufacturer’s specification.
4. Test for a signal wire short to ground and inspect the sensor output using the manufacturer’s prescribed circuit test.
5. If wiring and connector checks pass, test the phase V sensor and control module input before deciding which component has failed.

Common fixes

• Clean corrosion from the phase V sensor connector and restore secure terminal contact.
• Repair chafed or pinched phase V signal wiring shorted to ground.
• Repair the phase V sensor power or ground connection if testing identifies a fault.
• Replace the phase V current sensor if its output remains low with sound wiring.
• Repair or replace a control module only after confirming its input is faulty.

Can I keep driving?

A low phase V reading can trigger reduced torque, limp mode or a shutdown. Avoid relying on the vehicle for a journey if power is limited or unstable; continued use with unreliable current feedback can lead to loss of propulsion.