What it means
The vehicle hybrid control module detects a range/performance 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 checks whether its reading changes plausibly with operating conditions; this code sets when sensor C's signal is electrically present but falls outside the expected range or response pattern.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced
- Sensor element aged beyond calibration window
Symptoms
- Hybrid-system or powertrain warning light
- Reduced hybrid or electric drive power
- Cooling-system warning
How to diagnose it
- Review freeze-frame data and live sensor C readings from cold start through warm-up, looking for a value that changes too slowly or disagrees with other coolant readings.
- Inspect sensor C's mounting and connector for displacement, poor seating, corrosion, or harness strain that could affect its temperature response.
- Compare sensor C's reading with ambient and other available coolant temperatures under comparable conditions.
- Check the sensor C wiring, reference, and ground circuits for intermittent contact or resistance that could distort the reading.
- Test sensor C's response over temperature against the manufacturer's specification to determine whether the sensor has drifted.
Common fixes
- Seat sensor C correctly if it is displaced or poorly mounted.
- Clean and secure corroded or loose sensor C connector terminals.
- Repair wiring or reference/ground connections that distort sensor C's signal.
- Replace sensor C if its temperature response is outside the manufacturer's specification.
Can I keep driving?
The module may limit hybrid or electric power because sensor C's temperature reading cannot be trusted for cooling control. Avoid sustained high loads 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.