What it means
The current sensor for starter/generator phase Z reports voltage below the expected window. Indicates short to ground or sensor offset drifted low.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The starter/generator uses phase Z to exchange electrical power with the hybrid system, and its current sensor reports the phase current to the control module. P2D97 sets when the phase Z sensor signal is lower than the expected window, such as from a signal wire short to ground or a sensor offset that has drifted low.
Common causes
Most likely first.
- Signal wire shorted to ground
- Sensor offset drifted low
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or hybrid-system warning light may be on
- Reduced hybrid assist or regenerative charging
- Reduced engine starting or stop-start operation
How to diagnose it
- Record freeze-frame data and hybrid-system live data for phase Z current and related warnings to see whether the low reading is constant or tied to a particular operating condition.
- Inspect the phase Z current-sensor connector and accessible harness for corrosion, damage, loose terminals, or wiring rubbed through to ground.
- Using the manufacturer's wiring diagram, check the phase Z signal circuit for a short to ground and verify connector terminal condition.
- Compare phase Z sensor output with the other phase readings under the manufacturer's specified test conditions to identify an offset or circuit discrepancy.
- If the wiring is sound, test the phase Z current sensor and starter/generator system using the manufacturer's procedures.
Common fixes
- Reconnect or clean corroded phase Z sensor connector terminals.
- Repair the phase Z signal wire if it is shorted to ground or damaged.
- Replace the phase Z current sensor if its output is offset low and it fails the specified test.
- Repair the starter/generator or hybrid-system fault identified by the manufacturer's tests.
Can I keep driving?
Reduced hybrid assist, regenerative charging, or stop-start operation may occur, so avoid relying on those functions and drive gently to a safe service location if the vehicle remains controllable. If a hybrid-system warning is accompanied by loss of propulsion or other serious warnings, stop safely and seek assistance.
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.