Water temperature light flashing

Posted: Tue Jan 26, 2010 6:53 pm

The red water temperature/coolant level light in the centre of the dash display (where the autocheck would be) on my 1994 2.0 ABK is constantly flashing (in the same way an indicator light flashes). It comes on about 20 seconds after the engine has started running and does not go out.
The engine will run up to high 80 degrees then the fan cuts in and cools it down properly, it's not overheating in any way. I assume the water pump is doing it's bit as it's not being noisy or anything and the the idle is steady at about 850rpm.

I changed the thermo switch in the radiator about 300 miles ago and the coolant level has not dropped. I am sure the system has bled properly (it wasn't really a full coolant change and it all went back in), I've run the engine hot with the expansion tank cap off and the heaters on full.

I've read some other posts on here but they are a bit indecipherable, they suggest changing the thermostat and/or changing the sensor in the bottom of the expansion tank; others suggest some voltage thing in the dash itself.

If anyone has any fixes (and an idea of how hard it will be to do) I'd be grateful to know! Also, will it be ok to drive in everyday driving?

Audi Nut Joined: Apr 02, 2006 Posts: 87 Location: Coventry

This happened on mine and was a faulty sensor, one of the 2 that sits in the housing coming off the head, but off the top of my head I cant recall which one it was.

I'll have a look in the morning when its light and let you know.

Alan

Posted: Tue Jan 26, 2010 10:25 pm

Nice one, would you be able to get some pics up please showing where it was?

And also, how long were you driving it with the light on for?

Audi Nut Joined: Apr 02, 2006 Posts: 87 Location: Coventry

I'll see what I can do ref pics, had trouble loading them before.

Made sure first that the cooling system was ok, no leaks, fans cut in and out, temp guage didnt go high, and drove for about 2 weeks (150 - 200 miles), and all appeared ok.

This is what happened on mine though, would always recommend any vehicle with a cooling issue to be fully inspected first, used to work for Rover and saw too many K series engine die a needless death

Posted: Wed Jan 27, 2010 7:07 am

Nice one Al, I've had a look and as you say, no leaks, loss and fans work properly; I'm going to pull it through the final 120 mile commute this week (mostly motorway). I'f you can't upload the pics, I've PM'ed you my email address so you could attach them to an email. Thanks again.

Posted: Wed Jan 27, 2010 1:36 pm

A bit strange how this has started since changing the fan switch Confused

Audi Nut Joined: Apr 02, 2006 Posts: 87 Location: Coventry

Hi Dan

will try and get the pics to you later, but there are 2 sensors, 1 blue and 1 white/grey. If I recall correctly it was the white/grey I replaced, but Im sure someone can confirm which is which.

Al

Posted: Wed Jan 27, 2010 2:45 pm

I think it could be the MTFS. Exact same thing happened to my CQ20v - levels were all showing as OK as well. Best thing to do is get the fault code read out, i know you can make your own LED circuit, there is a how-to on somewhere on the forum. Easy and it works well.

Posted: Wed Jan 27, 2010 7:29 pm

Where can I find the Multifunction Temperature sensor on my ABK? - In fact, where can I find all of the above sensors mentioned?! If I was to buy any of them from GSF/motorfactors, do I ask for them as a MFTS etc, or are they stocked under a different name? Cheers!

Posted: Wed Jan 27, 2010 8:11 pm

not 100% sure as your engine differs from mine slightly....BUT... will probably be situated towards the front of the engine bay underneath the alternator/power steering pump on the side of the block. On my 5Cyl it is underneath the top radiator hose, just have a look about. Needs about a size 25 spanner or something it's pretty big. Will have a couple of wires connected to it in a connector block and also to the other sensors.

I know that was a crap explination but the best I can do lol!

Posted: Wed Jan 27, 2010 10:55 pm

sounds like it's needing bled.

Try lifting the expansion bottle up higher and squeezing the top rad hose.

Posted: Thu Jan 28, 2010 7:09 am

The if it is an airlock, it's only just manifested 300 miles since replacing the radiator thermo switch. Is this normal that a lock can develop?

Is this done by just removing the two screws that hold the tank or is there a bit more to its removal? Do I d this when the water is hot or can it be done when cold? Should the engine be running when I do it and do I leave the expansion tank cap off when I'm squeezing it?

Posted: Thu Jan 28, 2010 2:10 pm

have you tried pulling off the sensor wires under the header tank itself? and bridging them both together with a peice of wire

after all i fort that flashing light was a LOW COOLANT LEVEL indicator not over heating Confused

Posted: Thu Jan 28, 2010 7:55 pm

as per prevous replies - i had exactly this 3 times: once it was low level indicator going off properly after an airlock had cleared and allowed coolant to drop . (easy fix by topping up) the next time was the level sensor going wrong (replace reservoir with switch in) and the third was MFTS!

start at the beginning and work forward - MFTS was about £47!!!! Shock

Posted: Sat Jan 30, 2010 7:29 pm

Quick update - the light is no longer coming on (the bulb is working!) so I'm guessing it must be either an airlock which has cleared, or the level sensor has decided to play ball again. I did give the expansion tank a whack with my maglite while the engine was running having checked all the other sensor plugs were connected correctly. The bulb was still flashing after this but the next morning, no flashing Very Happy

Thanks everyone for your input.