Cooling Fan and Temperature Light always on

12th May 2015, 16:17

Hello everyone!

I've picked up an X-Reg 1.1 Saxo Forte recently and all was good.
I then took it on a long day of driving around the West Midlands and at the end of the day, it started to steam because water was hitting the exhaust manifold from the small holes on the neck of the water bottle.

I was a little surprised because I'd had no warning light come on and the fan wasn't running at all.

On closer inspection, I noticed that the yellow relay in the fan housing wasn't secured so I pushed it in further.

The next day (when I'd topped up the lost fluid), my temperature warning light stayed on and the fan came on, even though the engine was cold.
Every time since then, the fan and warning light are constantly on and the fan stays on for a few minutes after taking the keys out. It is definitely not hot.

I've noticed this problem has come up a lot but nobody seems to have given a definitive answer.

I've replaced the yellow relay (A)

Changed the coolant sensor (Blue sensor) (B)
(I presume this is the sensor on top of the thermostat with 2 cables coming from it - green and pink)

There is one more sensor which I've not yet changed but other posts haven't mentioned changing it (C)

I've disconnected the battery over night (positive and negative) to reset the ECU and I've bled the system (3 bleed valves flowing with water, heater on full heat - getting hot so no air lock in matrix and revved between 2000-3000rpm for a few minutes)

After doing all of this, I still can't get the temperature warning light off or fan to stop.

There is no sludge on the oil cap and no sign of oil mixing with water so I can rule out head gasket.

Anything I'm missing out to try to fix this problem? It seems kind of strange that plugging the relay in correctly triggered this.

Thank you =)

13th May 2015, 11:49

I've just done a code read on it which flagged up as p0115 which I'm aware relates to the coolant circuit.

Just need to know how to sort this out please

13th May 2015, 12:54

In addition, I've just got the multimeter out -
There is a 5V supply coming from the connector and continuity is reading at 1.1

There is also resistance in the sensor of 48000 ohms, and this changes when removed and placed in hot/cold water, so the sensor is definitely working.

I'm really struggling to get to the bottom of it.

18th May 2015, 16:33

I think I'm making progress. I am fairly sure there is a short circuit somewhere. This leads to my next question;

Where is the coolant system earthed to?

21st May 2015, 03:52

Had this happen on few vts"s over the years!!
ide check your earthing point...

21st May 2015, 06:10

Where is the earthing point?

I've seen some threads saying it's a connection to the ECU but other threads seem to contradict it and say it is elsewhere.

21st May 2015, 09:55

you should bleed it and perhaps replace the rad cap (if its knackered) to at least keep the system working as it should - electronics aside

21st May 2015, 10:38

Thanks Gandi699,

I've already bled it.
All 3 bleed points were flowing with water. The interior heater blows hot air after being bled so there are no air-locks in the system and heater matrix.

The radiator cap had a good seal, but I've just replaced that as a precaution.

21st May 2015, 16:14

An update:

In addition to bleeding the system, replacing 'A' and 'B' as mentioned in the initial post, and resetting the fault code P0115 found with a code reader, I've now done the following which appears to have fixed the problem!

1) Replaced the sensor labelled 'C' from my initial post
2) Replaced 2 x 30amp fuses from the fuse box under the bonnet
3) Replaced the radiator cap

Hopefully that will fix it for good.

17th September 2015, 09:45

I'm new here but I joined in to tell you my store about the "Cooling Fan and Temperature Light always on" problem.

Our Saxo 1.1 petrol overheated the other day due to a leaking cooling system and missing cooling fluid.

I refilled the cooling system but the temperature light stayed on and the fan ran for several minutes when the ignition was turned off although the engine didn't seem hot.

I took the car to the mechanics. While he changed the leaking cooler I googled the problem with the "Cooling Fan and Temperature Light always on" and it didn't seem to be a rare problem. Many good threads everywhere discussed the matter and many good suggestion was given how to solve the problem. The only solution to the problem suggested seemed to be to repair or replace the ECU.

If any broken wires to the temperature gauges or faulty temperature gauges were ever found and repaired so the problem was solved, it was not mentioned in the treads I read.

Then I did some deeper googling and this came up:

If the engine overheats the red temperature light will stay on but
there is no ECU (engine) light on. Whenever the engine is
running the cooling fan will run, it stays on for about 5 minutes.
Even if the ignition is switched on and off, without engine
start, this sequence is run. This cannot be reset by a
sequence of buttons but needs an OBD-II reset. Once the fault is cleared
everything will work OK.

The system works as follows: Sensor is NTC (negative temperature coefficient)
thermistor on thermostat housing, approx values of 20 deg C = 2500 ohm,
60 deg C = 500 ohm, 100 deg C = 180 ohm.

If sensor is disconnected the ECU will assume that it's faulty,
apparently all manufacturers design this way. The ECU drives
the fan through a relay so if the fan stays on it may be a
stuck relay (to be found here: http://www.citroen-owners-club.co.uk...ervicing-reset)

I called my mechanic and told him the essence of .

Now the car is repaired and the "Cooling Fan and Temperature Light always on"-problem solved.

He told me that since he didn't have the equipment to do the necessary ECU reset he took the car to a authorized Citroen workshop. When the mechanics there faced the "Cooling Fan and Temperature Light always on"-problem they started to troubleshoot the wires to the temperature gauges and the temperature gauges without any luck. My mechanics told them what I told him about the ECU reset and with great distrust they agreed on trying it out.

It worked. The temperature lamp turned off and the fan stopped.

I hope others can benefit from this story now and in the future.

PQR