What it means
The drive motor B rotor position sensor reports a circuit high fault. Phase commutation cannot be controlled reliably.
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 position sensor tracks rotor angle for hybrid motor phase timing. The module sets this code when the sensor circuit voltage is above its expected range, such as from a signal short to battery voltage or an open sensor circuit.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- 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
- Record freeze-frame data and inspect live drive motor B position-sensor values for a reading stuck high or inconsistent with rotor speed.
- Power down the hybrid system using the manufacturer's high-voltage safety procedure, then inspect the sensor connector for loose, corroded, wet, or damaged pins.
- Trace the signal wire for chafing or contact with a battery-positive feed, paying attention to harness bends and connector backshells.
- Follow the manufacturer's circuit test procedure to check for an open signal path and for a short between the signal wire and B+.
- Test sensor supply, ground, and signal at the sensor and control-module connectors to distinguish an open sensor from a harness fault.
- If wiring tests pass, test the drive motor B sensor against the manufacturer's specification and replace it if its output remains high.
Common fixes
- Repair a signal wire shorted to B+ or an open in the sensor circuit.
- Clean, secure, or replace corroded or damaged connector terminals.
- Restore the sensor ground or supply connection if testing identifies a fault.
- Replace the drive motor B position sensor if it is open internally or fails the manufacturer's specification.
Can I keep driving?
Avoid driving if the vehicle has reduced power, enters limp mode, or may shut down, because the control system cannot rely on drive motor B rotor timing. If it remains fully drivable, limit use and avoid demanding acceleration until the circuit is checked.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.