What it means
The hybrid control module detects that the power electronics cooling system does not maintain target temperatures under load. Coolant flow, radiator fouling, or pump output reduced.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid electronics cooling system carries heat away from components such as the inverter so they can operate within their temperature limits. The hybrid control module sets this code when cooling performance cannot keep electronics temperatures near target under load, and may reduce hybrid power to prevent overheating.
Common causes
Most likely first.
- Radiator fins fouled - reduced heat rejection
- Coolant aged - reduced heat capacity
Symptoms
- Check-engine light or hybrid-system warning
- Reduced hybrid power or performance
- Hybrid-system temperature warning
How to diagnose it
- Save freeze-frame data and check live inverter or power-electronics temperatures and cooling-system warnings to see when temperatures rise.
- When the system is cool, check the specified coolant level and look for leaks, discoloration, or signs of contamination.
- Inspect the electronics radiator or heat exchanger for blocked airflow, packed debris, bent fins, or damage that could reduce heat rejection.
- Check for restricted or kinked coolant hoses and verify that the electric cooling pump operates as commanded, using the manufacturer's procedure.
- If airflow, coolant, and pump operation appear normal, have coolant circulation and temperature sensor readings checked against the manufacturer's specification.
Common fixes
- Remove debris from the electronics radiator or heat exchanger without damaging its fins.
- Repair coolant leaks and refill or renew the coolant with the specified type using the manufacturer's procedure.
- Replace a failed cooling pump or repair a restricted hose.
- Replace a faulty temperature sensor or repair its wiring if testing identifies an incorrect reading.
Can I keep driving?
Avoid heavy acceleration, towing, and long climbs, especially if a hybrid temperature warning appears or power is reduced. Stop safely if the warning persists or temperatures continue rising, since overheating can damage the inverter and disable hybrid drive.
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.