C3 mk2 cooling fan coming on when stationary

[Spheniscidae]

My daughter has a 2010 C3 Mk2 1.6 VTI Auto.

Recently, the cooling fan started coming on when she stopped/parked up the car. It stays on for about 5 mins and then goes off. I have driven it the last couple of days and this also seems to apply when driving. If you come to a roundabout or traffic lights and have to stop, then the fan quite often comes on. It goes off shortly after you're moving again.

I have replaced the coolant temp sensor, thinking it may be sending dodgy info to the ECU, but still the same. Should I be looking at the fan control unit? If so, does anyone know what the correct, current, part number would be for one? Citroen are wanting nearly £100 for one.

Any advise is more than welcome.

Thanks in advance

[mickthemaverick]

Possibly a daft question but have you bled the cooling system, it sounds to me like you may have an air lock which travels round the cooling system and causes the problem when it reaches your sensor? Just a thought

[PaulC5]

Does it do this with the air con turned off ?

Our 2010 C3 with the 1.4 vti engine had a problem where the fan kept coming on when not needed and it turned out there was a known fault with the temperature sensors. Citroen's fix was to fit a second sensor in the thermostat housing bleed point along with a short wiring loom and leave the old one in place. This was done at no cost to us. It was not a fault where they did a recall, only when I went to buy a new sensor was I told and they did the repair. This was around 2014.

[ozvtr]

I had a problem with an earlier model C3. Our C3 models are not even similar, but the engineering principals might be the same?
Randomly when I stopped the car, the radiator fan would run on when the engine was turned off. I have had problems with radiator fans before, so I initially suspected the fan. But it was only "now and then".
Then one day when the car was on the freeway at speed, the engine over heated. Turned out to be a blocked radiator. But it gave no signs before suddenly over heating (except for the fan).
Since changing the radiator, the radiator fan has not run on after the engine is shut down!
The older (Mk1) C3s have 6 LEDs to indicate the temperature. 3 LEDs is normal running temperature. It never showed more than 3 LEDs BEFORE the engine over heated. When I limped home on that day the temperature could be seen to go over the 3 LEDs up to the 6th LED. I had to put the heater on Hi and full speed on the interior fan to keep the engine temp down.
The only conclusion I can draw from this is that the radiator fan WILL run on after the engine is shut off, IF the coolant is above a certain temperature. And that assumes that the radiator fan is not faulty!!!
I do not know if this is your problem, but the radiator is one thing to consider.

[PaulC5]

If not done before, use a code reader with live data to see what temperature the sensor is giving. Normal running the coolant is probably about 90 to 96°C and above this the fan ought to run but see what temperature the fan is starting and stopping.