What it means
The vehicle hybrid control module detects a circuit low 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 watches its signal to assess cooling needs; this code sets when the signal is abnormally low, often because the signal wire is shorted to ground or the sensor has an internal short.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
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 temperature, comparing it with other coolant readings when cold and warmed up.
- Inspect sensor C's connector and harness for corrosion, moisture, damaged insulation, or a signal wire contacting ground.
- With the vehicle powered down as specified by the manufacturer, check sensor C terminals for corrosion, looseness, or poor contact.
- Use the wiring diagram to test sensor C's signal circuit for an unintended connection to ground and check its reference and ground circuits.
- Test sensor C against the manufacturer's specification and compare with the harness-side signal to identify a shorted sensor versus wiring fault.
Common fixes
- Clean and secure corroded or loose sensor C connector terminals.
- Repair a signal wire shorted to ground or other damaged wiring in the sensor C circuit.
- Replace sensor C if it fails testing.
- Clear the code and verify sensor C readings are plausible in operation.
Can I keep driving?
The module may reduce electric or hybrid power because it cannot judge power-electronics cooling correctly from sensor C. Avoid demanding driving 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.