What it means
Phase Z current of drive motor A exceeds the expected window. Indicates phase short, stalled rotor, or sensor offset.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The inverter controls current in drive motor A's phase Z winding, while the hybrid control module monitors that current through a sensor. This code sets when phase Z current exceeds its expected range, which can result from a short between motor phases, a stalled rotor, or a sensor offset.
Common causes
Most likely first.
- Short between motor phases
- Rotor stalled - high stall current
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Save freeze-frame data and compare phase Z current with phases X and Y, noting the motor speed and load when the high reading occurred.
- Check related motor, inverter, and rotor-position codes for evidence of a short or a rotor that is not responding as commanded.
- Disable the high-voltage system according to the manufacturer's procedure and inspect phase Z and neighboring phase wiring for damaged insulation, melted areas, or arcing.
- Have the drive motor phase insulation and winding condition tested using the manufacturer's procedure and suitable high-voltage equipment.
- If the winding checks pass, test the phase Z current sensor and inverter measurement circuit for offset or internal failure.
Common fixes
- Repair damaged phase Z wiring or connectors if the fault is external.
- Replace a phase Z current sensor that fails its test, if separately serviceable.
- Repair or replace drive motor A if a phase-to-phase short is confirmed.
- Repair or replace the inverter if its phase Z measurement or switching circuit is faulty.
Can I keep driving?
Stop safely and arrange recovery if the vehicle loses power, makes unusual motor noises, or smells burnt; excessive phase Z current can damage the motor or inverter. Otherwise, avoid hard acceleration and heavy loads until diagnosed.
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.