It's that same old question I'm sure a good few have already asked, my thermostat is flashing!!!! I have a mk2 8v 1991 gti , I have flushed out coolant topped up with new and stays at level, replaced all sensors 'blue,black, rad switch'. No leaks all air tight, fan does kick in when it should and cuts out no issues there. I have by passed alllll sensors and still flashes, checked wiring near connectors and all intact not exposed or broken, so what else could it be ?????? Please staple the answer to my forehead as it's about to implode many thanks
Could be the instrument cluster I had a motometer one do this to me before. Soon as I changed it to a Vdo one it stopped.
I have a 16v gti, so not sure the bottle is the same, but i had this issue it turned out to be the plug connecter you plug into top of expansion bottle sensor had abit of corrosion and the metal connecters inside were not touching properly must of weekend a little i just cleaned it all out then had a fiddle with them works fine now. I realised you have checked but thought might be worth a second look of that connecter inside
try loopign a bit of wire between the 2 pins on the level sender if you haven't already. if it still flashes unplug the dash temp sensor next and try again. if it stops the temp sensor is bust or its a clocks issue, if not its the level warning system or clocks at fault. if you drop the fusebox down look for plug C, stuff a wire in the back of the plug between pins 5 and 8 see if that stops it. if it does its a wire issue in the loom or pin corrosion as mentioend on the level sender. look close at the back of the plug where the wires go in for signs of damage, and give the wires a light tug to see fi they are ok to the back of the terminals. its a right bugger when they snap off inside where you cant see so all looks fine on the outside
I had this a while back. Replaced every sensor I could think related to temp and it was my vdo clocks Bought a set off ebay. Swapped speedo and all was good.
Thanks for the advice guys, it seems it may be my clock's at fault. Was it easy to swap the Speedo ??? Thanks
I had this issue on my MK3, was found to be a faulty cluster in the end. Dead frustrating, I have felt your pain
Hello guys just a quick one, big thanks to everyone for the help and advice. I strongly recommend going through the process of elimination of changing sensor first, by passing the sensor's and then looking at the clock's. Was really easy to swap the Speedo onto a work clock and if this hadn't of worked I would then assume some faulty wiring.
I changed temp sender, thermostat, fan switch, coolant bottle. Lid....and no joy. Changed clocks and hey presto!
I had a polo that did the same it never bothered me enough to fix it It didn't over heat the temperature gauge worked and never used water and level was fine The level switch worked Just had this random flashing due to the clock being duff very common on that age of polo
its possible the dash temp sensor is to blame as well, my mates mk2 was doign this and I was pulling out my hair trying to figure it out till eventually out of desperation I put my dash sensor ion there and it was fixed the dash temp worked perfectly fine too which is why it drove me round the bend. All I can think of is it was intermittently shorting to ground inside, which was enough to trigger the level/temp warning but not cause the gauge to rise.
For me, the ground was failing.. I noticed it happenening more at night and dash lights dim. Found the column hex was loose, tightenened it and came good. Later I ran a new ground to earth block too. Ps.. mine was intermittent and took over a year to resolved
