Drivable — worth looking into
The cooling fan runs all the time
The fan roars right after starting and does not stop even on a cold engine or in frost.
There is no danger, but the symptom will not go away by itself: it is the early stage of something that gets pricier.
What to look at in the live data
- Coolant temperature on a cold car: it must match the air outside.
- How the temperature rises during warm-up: a permanent fan at an honest 90 °C and at an invented 120 °C are different stories.
- Temperature sensor faults: an open circuit is often read as overheating, and the unit turns the fan on just in case.
Common causes, cheapest first
- The temperature sensor reads high or is open — the unit plays safe and keeps the fan on.
- The fan relay has stuck: then it runs even with the ignition off.
- The car really is running hot and the fan is honestly doing its job — visible in the temperature itself.
Codes that show up with this
P0116Engine coolant temperature circuit range/performanceP0117Engine coolant temperature circuit low inputP0118Engine coolant temperature circuit high inputP0128Coolant thermostat — temperature below regulating temperatureP0480Cooling fan 1 control circuit malfunction
These parameters in the reference
Lamps that may be on
Do it step by step
Weak heater and higher fuel use? One graph answers the question in ten minutes.How to tell whether the thermostat is to blame
A symptom is not a diagnosis. The same sign comes from a dozen different causes — the readings are what tell them apart, not the feeling.
How the app helps
CarScan shows exactly these readings live, remembers the highest and the lowest value of the trip, and puts them into a report you can hand to a mechanic.