What it means
The vehicle hybrid control module detects a circuit fault on the coolant temperature sensor C that monitors the power electronics cooling loop.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Sensor C measures coolant temperature in the hybrid and EV power-electronics cooling loop. The hybrid control module monitors its circuit for a usable signal; this code sets when it detects an electrical fault in the sensor C circuit, without specifying whether the signal is low or high.
Common causes
Most likely first.
- Sensor failed
- Wiring or connector fault
Symptoms
- Hybrid-system or powertrain warning light
- Reduced hybrid or electric drive power
- Cooling-system warning
How to diagnose it
- Check freeze-frame data and live sensor C readings for missing, erratic, or implausible temperatures, comparing with other available coolant readings.
- Locate sensor C using vehicle service information and inspect its connector and harness for damage, corrosion, moisture, or loose terminals.
- With the vehicle powered down as specified by the manufacturer, check sensor C connector contact and look for a pushed-back or spread terminal.
- Use the wiring diagram to check sensor C's signal, reference, and ground circuits for opens, shorts, or poor connections.
- Test sensor C against the manufacturer's specification and compare its response with the harness-side circuit to isolate the fault.
Common fixes
- Clean and secure sensor C connector terminals if contact is poor.
- Repair damaged wiring or a poor connection in the sensor C circuit.
- Replace sensor C if it fails testing.
- Clear the code and verify sensor C produces a stable, plausible reading.
Can I keep driving?
The hybrid system may reduce electric drive power because it cannot rely on sensor C to assess power-electronics cooling. Keep loads modest and stop safely if a cooling warning or overheating indication appears.
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.