● Can wait
Usually no immediate risk. Book it in, and watch for new symptoms.
Usually no immediate risk. Book it in, and watch for new symptoms.
The engine stays below its normal regulating temperature. The driver may notice a low temperature gauge, weak cabin heat and higher consumption.
Guided check
- Is the coolant level low?If yes: Top up and look for the leak, then test again.
- Does the top hose get warm early, soon after a cold start?If yes: The thermostat is probably stuck open. Replace it.
- Does the temperature sensor reading differ from an infrared thermometer?If yes: Check the sensor and its wiring before replacing the thermostat.
These checks are general and are still being reviewed by working mechanics.
Causes vary by car. Test before you order a part.
Likely causes, most common first
- Thermostat stuck open
- Faulty coolant temperature sensor
- Low coolant level
- Cooling fan running all the time
Parts usually involved
- Thermostat Find at suppliers
- Coolant temperature sensor Find at suppliers
Test before you replace
Watch live coolant temperature on a road test and check that the upper hose stays cool until the thermostat opens.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.