What it means
The ECM detects a low fault on the hybrid/ev electronics coolant temperature sensor a circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid/EV electronics coolant temperature sensor A measures coolant temperature in the circuit that cools high-voltage electronics. The ECM monitors its signal, and this code sets when the signal is lower than the circuit’s expected range, so the temperature reading cannot be trusted for cooling control.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Hybrid or EV system warning light on
- Reduced power or limited vehicle operation
- Cooling-system warning may appear
How to diagnose it
- Review freeze-frame data and live sensor A temperature to see whether the reading is implausibly low or changes with the fault.
- With the vehicle powered down as directed by its service information, inspect sensor A and its connector for moisture, corrosion, damaged seals, or bent pins.
- Check the sensor A signal wire for a short to ground and inspect the harness for chafing or pinching.
- Check the connector terminals and ground reference for poor contact or corrosion that could distort the signal.
- Test sensor A and its circuit against the manufacturer's specification to distinguish an internally shorted sensor from a wiring fault.
Common fixes
- Clean or repair corroded sensor A connector terminals and restore a sound connection.
- Repair a signal wire shorted to ground or damaged harness section.
- Replace a faulty hybrid/EV electronics coolant temperature sensor A.
- Clear the code and confirm the live temperature reading is plausible and stable.
Can I keep driving?
Treat reduced power or a hybrid/EV cooling warning as a reason to stop driving and arrange inspection; the system may limit operation because it cannot reliably assess electronics coolant temperature. Avoid demanding acceleration or long trips, since inadequate cooling protection could allow high-voltage components to overheat.
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.