Water temp indicator failure!!!!!!!!

Hi All, I got in my car this afternoon for a drive from Leics to Heathrow to pick up the enemy. Within a few minutes the red light at the top of the water temp guage started to flash and a warning 'indicator failure' refering to the water temp guage. At first i was quite worried and pulled over a few times to check the water but everything okay. During the journey this happened quite a few times, it would be okay and show the temp, then it would fail giving the warning and flashing light. When working the temp reached just over 60 which usually sits at just over 80, indicating 20 less than 'normal'. As this was reflecting cooler water temp i hoped it would not be an issue. Better cool than hot! On the way back from Heathrow the temp guage decided to work for the whole journey but still sat at just over 60. Can anyone help?? The car is due for a service and in 4 years nothing has gone wrong except wear and tear (tyres, brakes) but i would hope to diagnose the problem and fix before the service if possible unless my OPC does not charge the earth for the repair although i'm sure they will. I know some experts who are friends and know they will be able to help but they are not local to me and hope to diagnose here. It is a 2002 996 Facelift Tiptronic C2. Thanks

I would suspect the coolant temperature sensor. They are only £10, so if it was me, that's where I would start. Not too sure how easy it is to get at - it is screwed into the side of the oil pump. A diagnostic check on the instrument cluster migh reveal more information. The flashing light is a bit odd though: Four functions of the coolant warning light: 1. Engine coolant level too low "” light flashes slowly (0.5 Hz) 2. Engine compartment temperature too high "” light flashes slowly (0.5 Hz) (engine compartment blower might be faulty) 3. Engine coolant temperature too high "” light is lit; pointer on the right 4. Temperature sensor at water outlet faulty "” light flashes rapidly (1 Hz); pointer on the right

on top of what richard says i have had it where the air pipe which is connected to the shutoff valve on the side of the tip box comes off causing this problem too...

Hi Richard, thanks for your help, i will try this first. Any chance you know the part number for the item? My car is a 2002 Facelift 996 Tiptronic 3.6 Carrera 2. Is it possible for me to do this myself or is this just silly!!! You have been very helpful and i would like to return your help. My company is a sub-distributor for Kaspersky, so i have a few 3 month free trials, which i can send you the code for if you are interested. You can download a free 30 day trial from the Kaspersky website and i can send you a code for 3 months free which you can use when the 30 day expires. This is internet security 2009. Thanks Bobby

I've never done it, so I have no idea of the degree of difficulty. Part number is 996.606.410.00 at £9.90 +VAT. I think I'd be tempted to try porscheuro's suggestion first - he's pretty good at this sort of thing.

Hi Porsheuro, Thanks for the advice, can you give me any advice on how to locate this air pipe. Thanks

the air pipe that may be at fault is located at the underside of the vehicle on the n/s of the tip box, you will also find it has undertray covering it too, all the pipe does is operate the cooling for the gearbox and if it doesnt operate it throws the light on the temp gauge on.. will try get an image..

Hi Porsheuro, Thanks for the advice, looking forward to any more details you can give. Was wondering if this is the same problem as you have had. The water temp indicator fails, bleeps once, reporting no temp and the red light flashes slowly. Then it comes back on after a while and reports the water temp as 20 degrees below what it usually shows i.e sits just above 60 degrees and usually sits just above 80 degrees. Apart from this the car operated perfectly, but this did happen many times say 20 during my 300 mile journey to London and back on the same day. Does this sound similar to the one you had?? Thanks so much

looking like it may be a temp sensor fault, this is situated on the n/s of the engine just behind the auxilary belt , a black plug... would still check the vac pipe on the water valve on the tip box as this may be causing varying temp when it opens and closes to let water into tip box cooler..

That's also what's been suggested on renntech.org, so I would definitely check it out first If I were you.