Radiator fan is constantly on, anyone help?

**fuzzbomUK** · 25th November 2008, 20:14

Hi all,

Yet again more problems with my Vectra.
As im sure you can guess, my radiator fans are constantly on.
I have plugged the old op-com in and it comes back with error code P0115.

P0115 Engine Coolant Temperature Circuit Malfunction

Have checked all cables etc and all look to be ok, the fans even continue running when the engine is off for about a min or 2.
Its almost as though the engine thinks it over heating.

I have read elsewhere that there is yet another control unit that controls the cooling.
The biggest down side is that the engine does not heat up at all, and its making it drink petrol.

Any suggestions welcomed,
Thanks

**Big Sig** · 25th November 2008, 20:38

I'd make a guess at the temperature sensor and/or the thermostat. My reason being the ecu may be wondering why the engine is always cold - because the thermostat is stuck; but this would not keep the fan on. So it could be because the sensor has dies giving false readings to the ecu so it thinks its always cold. Have you checked the hoses to see if they are warm when the engine is running? Do you get heat from the car heating????

**fuzzbomUK** · 25th November 2008, 21:21

Thanks for reply.
Funny you mention the thermostat, I have already done it as the car had warming up problems.. It was stuck open.
But i have never noticed the fans on before.

I have pulled the power to the fans and the engine does get up to operating temp, and yes the pipes do also get warm.
As for heating... there is some heat but it is minimal

The temp gauge in the car will rise to normal temp if fans unplugged, are there 2 sensors? one for ECU and one for instruments?

**Big Sig** · 25th November 2008, 21:32

I'm not sure how many there are but I would imagine there is only one. Its normally mounted in or very close to the thermostat housing. Its most likely have a single or a couple of wires going to it and a push on plug type arrangement. TBH I would try this next, I wouldn't have thought it would be too expensive and it seems logical to me. Hopefully someone else will be along with a second opinion too

edit: forgot to add that I would think that the sensor would also control the fans i.e. if it thinks its too hot then it will bring the fans on.

**fuzzbomUK** · 25th November 2008, 21:47

I agree it does have all the symptoms of the ECU thinking the engine is really hot. Fans running on etc. when engine off.
I’m pretty sure I know where switch is, will get one on order.
Not near the thermostat on a 3.2 though it’s the battery side of the engine (I think)
All the other electrics are there so I guess it would make sense to put it there.

If i clear the fault code and start the engine it will run fine, but then on next restart fans on yet again.
Can’t keep resetting the poxy fault code each time lol.

**Big Sig** · 25th November 2008, 21:50

No I agree. Its needs a permanent fix

**fuzzbomUK** · 26th November 2008, 11:15

I have just called VX, they informed me that these engines do not have a temp sensor as such, they have yet another control unit.
its £50 inc vat and has to be tech2'd into the car...

Anyone else had this problem before?

**fuzzbomUK** · 29th November 2008, 18:04

Just a quick update on this..
Turned out not to be the control unit thingy, was sold the wrong thermostat my local VX dealer!!!
The thermostat on the 3.2 has been revised 3 times, mine had the original on it so had to get whole housing to fit a new stat.
The fans were permanently on because the engine wasn’t getting to the correct temp in a preset time so it was going into protecting mode. (Was told this by ex VX mechanic)

Engine now warms up better than ever and running great.