What it means
The current sensor for starter/generator phase X 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 X current sensor measures current in that specific phase so the control module can regulate assist and charging. This code sets when the phase X reading is outside the expected operating range or does not track as expected, even if the circuit is not electrically open or shorted.
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 X current readings, checking whether the mismatch appears at rest, during starting, or while charging.
- Compare phase X readings with phases Y and Z under similar conditions to determine whether the abnormal measurement is isolated to phase X.
- With the system safely powered down, inspect the phase X sensor mounting and surrounding area for looseness or nearby magnetic parts that could affect its reading.
- Inspect the phase X sensor connector and harness for corrosion, damage, poor seating, or routing changes.
- Check sensor supply, ground, and signal behavior against the manufacturer's specification.
- If the circuit and installation are sound, test the phase X sensor for offset drift or age-related calibration error before replacing it.
Common fixes
- Secure the phase X sensor and correct its position if it has shifted.
- Restore the original routing or clearance if nearby parts are affecting the phase X sensor.
- Clean and reconnect a sound but poorly seated phase X sensor connector.
- Repair phase X sensor wiring or ground faults found during testing.
- Replace the phase X current sensor if its offset remains out of specification.
Can I keep driving?
The control module may limit starter/generator assist or charging, and the vehicle may start less smoothly. Avoid demanding trips until checked; stop safely if starting becomes unreliable or the hybrid warning worsens.
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.