Seat Ibiza Mk4 2003 Tdi. Problems Temp Guage.
 

Son has a 2003 Mk4 Tdi Seat Ibiza. Had to refill the power steering reservoir today which meant removing battery and tray to get to it (stupid design !). Reconnected afterwards, followed ignition on /off routine as per handbook, car starts , runs etc all dials work EXCEPT temp gauge. It was fine before but now seems stuck on 50 degrees, doesn't drop to zero with ignition off which it did before.
So what has happened, any ideas ?
Cheers
Brian.

try a new temp sensor, there know for being crap, get genuine about £40 iirc