What it means
The current sensor for starter/generator phase Z reports a circuit 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 Z current sensor measures current in phase Z so the control module can manage assist and charging. This code sets when an electrical fault in the phase Z sensor circuit prevents the module from trusting that current reading.
Common causes
Most likely first.
- Current sensor failed
- Wiring fault
Symptoms
- Check-engine or hybrid-system warning light
- Reduced starter/generator assist or charging
- Rough or reduced engine starting assistance
How to diagnose it
- Scan for related hybrid or charging codes and review freeze-frame and live phase Z current data to understand when the fault appeared.
- With the vehicle safely powered down under the manufacturer's procedure, inspect the phase Z sensor connector and harness for looseness, corrosion, abrasion, or heat damage.
- Check phase Z sensor wiring and terminals for opens, shorts, or poor connections against the manufacturer's specification.
- Inspect accessible grounds and sensor power feeds for loose or damaged connections.
- Compare phase Z readings with phases X and Y under similar operating conditions to check whether the fault is isolated to phase Z.
- Test the phase Z sensor and circuit according to the manufacturer's procedure, replacing the sensor only if wiring and connections are sound.
Common fixes
- Reconnect a loose phase Z current-sensor connector.
- Repair damaged phase Z sensor wiring or terminals.
- Restore a faulty phase Z sensor ground or supply connection.
- Replace the phase Z current sensor if the circuit checks correctly but the output remains faulty.
Can I keep driving?
The vehicle may reduce starter/generator assist or charging, which can make starting less smooth. Keep trips short until diagnosed and stop safely if the vehicle has trouble starting 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.