Coolant temp/thermostat/boiling ABC V6

[fourringsrus]

The car; 1995 N reg Audi coupe 2 wheel drive, 5 speed manual, 2.6 v6 ABC.


I parked the car up at the end of January when I bought an Audi 90, at the time I had experienced a boil up which I put down to the cooling fans not kicking in when I had just given her a hoofing down the motorway.
On my usual run approx 7 miles to work, I had no more issues as I assumed she never got hot enough on such a short run.
While sat on my drive I occasionally started her up just to keep the battery up to scratch but recently having started her I forgot she was running and she boiled over, but on this occasion I noted that the cooling fans were running.

Fast forward to today, having booked an MOT test for this weekend I bought a new battery and fitted it, having first checked oil, coolant etc.
She fired up instantly, but oddly the coolant temp symbol (thermometer) was flashing immediately (ie; when stone cold )
Eventually the temp gauge came up to 90'ish, but the other symbol was still flashing.
The heater is blowing luke warm and I had previously suspected the matrix was dud, but now I am wondering if the thermostat is jamming as she got very warm before the reservoir level went down and then back up and overflowed. (cap was off trying to let her sort of self bleed )
I shut her off and let some pressure out of the reservoir, thinking I had a circulation issue, thermostat or water pump possibly, but now she seems to be happily sitting at idle and at 90 degrees, but the flashing thermometer is still flashing.
Tell me please what are your opinions on what is going on here.

Many thanks in anticipation

Stuart

[fourringsrus]

Right tried her this evening and flashing thermometer almost instantly I fired her up.
Whats going on here, I need to go for mot this Saturday and am informed that any lit warning light will result in a failed test
Assuming I have a sender/sensor issue where and which needs temporarily disabling, just to get me past the test time,until I can source new or remedy the situation.
Please help urgent
Many thanks

Stuart

[zollaf]

on my 16 and the tdi, there is a sensor in the header tank. don't know if this is the problem, but my new tdi does this and tomorrow when shes back together with another header tank i will know for sure .

[fourringsrus]

Thanks Lawrence, just had the tank off and wiggled wires etc, sorted...( for now )

[fourringsrus]

Took the coupe and the a90 both for mot today............two old Audis with new mot sheets,...yipeee
Advisories,,,,,,,,,n/s track rod end on the 90...........o/s drop link on the coupe, both slightly torn rubbers, will be nice cheap and simple to sort