What it means
The current sensor for starter/generator phase Y reports a circuit range/performance 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
The starter/generator’s phase Y current sensor measures current in phase Y so the control module can regulate assist and charging. This code sets when the phase Y reading falls outside its expected range or fails to track correctly, indicating a performance or calibration issue rather than simply a circuit fault.
Common causes
Most likely first.
- Current sensor offset drifted
- Magnetic offset from nearby parts
- Sensor element aged beyond calibration window
Symptoms
- Check-engine or hybrid-system warning light
- Reduced starter/generator assist or charging
- Rough or reduced engine starting assistance
How to diagnose it
- Review freeze-frame data and live phase Y current readings to see when the value departs from expected behavior.
- Compare phase Y readings with phases X and Z under similar operating conditions to confirm whether the mismatch is specific to phase Y.
- With the system safely powered down, check that the phase Y sensor is secure and inspect nearby parts for magnetic interference.
- Inspect the phase Y sensor connector, wiring, and grounds for poor seating, corrosion, or damage.
- Check the phase Y sensor supply and signal against the manufacturer's specification.
- If the installation and circuit are sound, test the phase Y sensor for offset drift or aging before replacing it.
Common fixes
- Secure the phase Y sensor if it has shifted.
- Correct nearby magnetic interference or sensor routing if found.
- Clean and reconnect a poorly seated phase Y sensor connector.
- Repair faulty phase Y wiring or ground connections.
- Replace the phase Y current sensor if its reading remains outside specification.
Can I keep driving?
Starter/generator assist or charging may be reduced, and engine starting assistance may feel rough or weak. Avoid relying on stop-start or hybrid assistance until checked, and stop safely if starting becomes unreliable.
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.