New sender water temp fitted in April and new 'stat fitted a month back.

surely the sender has failed (again)

I was sitting ont he motorway at 90 degrees, then it dropped suddenly to just abive minimum, then it picked up after 2 miles but dropped soon after.

GSF are sending me a new sender

Any other ideas?

Car has been fine since new 'stat and sits at 90 nicely

Ive a 1.8T Audi 2004 A4 with the same problem for ages (though my temp just drops quickly)

firstly I changed the water pump as its a common fault on the 1.8T as they have plastic impellars that shatter - bought upgraded metal impellor version. changing the water pump also means I may as well change the cam belt

this didnt fix it but then i found a tiny leak, replaced the hose and this didnt fix it either

then i changed the temp sensor and this didnt fix it.

then i found out about another temp sensor and changed that one and that didnt fix it.

ive now decided its the guage and given up, everything gets up to and statys at temp so i dont know what else to do.

my a4 has a dodgy one as well, most of the time it doesn't work everynow and agian it does and sits nicely in the middle of the gauge, I assumed its a dirty connector but being lazy I've not looked, its got oil temperature as well so I'd spot it overheating. There are two senders one for the gauge and one for the ecu, VAG Com will give you the reading from the other sender that feeds the ecu.

So far the temp sender on my polo (same as the golf ones I believe) has needed to be replaced almost every 2 years.... Rubbish little things...

I know a few people get sporadic needle movements if the earth bond to the clocks is faulty... I believe a common issue on the 6N2 polo chassis... not sure if others suffer the same

Surely overheating would be caused by a faulty pump? Not the reverse of cold water readings at random intervals?