Coolant temp gauge

[Richyy]

Hi all,

A4 B6 3.0 V6 petrol quattro

Got a issue with my temp sensor on my instrument cluster keeps changing its mind, I've seen it go from 90 to 0 then back to 90 but never goes over 90. I noticed a crack in the coolant overflow so got a new one and fitted it, once fitted I burped it and still doing the same. 

So my next plan of attack is to change the temp sensor. Main issue is not actually knowing what this involves as I can't find anything that is clear and for my engine. I've got a plug on the overflow but underneath, my guessing is that the leak has damaged the wire somewhere as the crack was on the underside also. But it seems to be the only one I can find and seems to go into the bulkhead so guessing it's the one that plugs into the cluster.

Is this gunna be a pig of a job? Also in my head this should solve the issue anyone had the same or similar? any help is appreciated

TIA 

Richard