What it means
The drive motor B rotor position sensor reports a circuit 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 reports rotor position so the inverter can time current to that motor's phases. The hybrid control module monitors the sensor circuit and sets this code when it detects a fault that makes position feedback unreliable. The code identifies Drive Motor B, so diagnosis should focus on its sensor, connector, wiring, and inverter input.
Common causes
Most likely first.
- Position sensor failed
- Wiring fault
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Scan for related hybrid codes and review freeze-frame and live data for Drive Motor B rotor position, motor speed, and sensor status.
- With the vehicle powered down according to the manufacturer's high-voltage safety procedure, inspect the Drive Motor B position-sensor connector and harness for damage, corrosion, or a loose connection.
- Check the sensor wiring for continuity, shorts, and connector pin condition using the manufacturer's wiring diagram and specifications.
- If available, compare Drive Motor B position readings with motor speed and commanded operation for dropouts or implausible values.
- If the circuit checks pass, test the Drive Motor B position sensor and inverter input using the manufacturer's diagnostic procedure.
Common fixes
- Reseat a loose Drive Motor B position-sensor connector.
- Repair damaged wiring or corroded terminals in the Drive Motor B sensor circuit.
- Replace the Drive Motor B position sensor if circuit testing confirms it has failed.
- Repair the inverter input only if testing confirms it cannot read a sound sensor signal.
Can I keep driving?
Avoid hard acceleration and high-speed trips while the hybrid warning is on, since unreliable Drive Motor B position feedback can reduce torque, trigger limp mode, or lead to shutdown. If power becomes unpredictable or a stop warning appears, pull over safely and arrange recovery.
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.