C5 fan keeps coming on !

reacher · Post by **reacher** » 31 Oct 2009, 15:42

The engine coolant fan keeps coming on sometimes even when the engine is cold, it stays on for about 15 minutes even after switching engine off. Is this a sensor problem?, I could do with pointing in the right direction. Its the 2005 face lift Lx version. 1.6 HDi C5, this is driving me up the wall. The temp gauge never shows over heating.

HDI · Post by **HDI** » 31 Oct 2009, 16:09

Simplest thing first , check coolant level.

reacher · Post by **reacher** » 31 Oct 2009, 17:52

Thanks HDI, the coolant level is ok.

HDI · Post by **HDI** » 31 Oct 2009, 18:07

Very likely to be the coolant temp sensor then. Does this car have aircon ?

reacher · Post by **reacher** » 31 Oct 2009, 18:25

yes it has aircon. If its the sensor I wonder why the temp gauge always reads normal or lower?

HDI · Post by **HDI** » 31 Oct 2009, 18:46

Not sure about the C5 1.6 HDI , but some have a sensor for the temp gauge and one for the ECU which controls the fans. The fans also run for the aircon so try switching that to see if there is any effect on the fans.

reacher · Post by **reacher** » 31 Oct 2009, 20:26

Thanks HDI, according to Haynes there is only one sensor. I will try the aircon next time it happens.... so it wont be long!

Reacher

VertVega · Post by **VertVega** » 31 Oct 2009, 21:09

Only one, thats' interesting

In mine there are 3 different temperature sensors (fans, gauge, injection) on the thermostat housing.

reacher · Post by **reacher** » 31 Oct 2009, 21:23

Three, now that is interesting! Answering this now while those tyo rubish lads are on xfactor!

Reacher

VertVega · Post by **VertVega** » 31 Oct 2009, 21:49

Yep, in my petrol Xantia there are 3 of them in a row, green, brown and blue

Edit: The reason why I was surprised, because one sensor should control fan(s) and
another supply temperature data to the instrument panel gauge.
But may be this is different in a diesel model

reacher · Post by **reacher** » 31 Oct 2009, 23:00

sorry about spelling in last post, was not wearing my glasses!
According to Haynes, the one sensor signals the ecu(or whatever its called) and then the ecu controlles the gauges and fan etc.

Reacher

reacher · Post by **reacher** » 03 Nov 2009, 18:56

Have tried switching aircon on and off when the fan is on, it makes no difference. It seems to be coming on more as the weather gets colder which sounds daft. Probably have to try and change the sensor, see if that cures it.

reacher · Post by **reacher** » 06 Nov 2009, 20:24

anyone know if its easy to change the senser? Could it be something else?

wheeler · Post by **wheeler** » 07 Nov 2009, 01:17

I really cant see it being a sensor problem as the gauge is working perfect & it is the same sensor. I'd say either a sticking relay or an ECU software problem, may be worth checking with citroen to see if there is a newer version available.

reacher · Post by **reacher** » 07 Nov 2009, 10:03

Thanks wheeler, you have given me something to go on.