Hmm, on the 1.4 the plugs are quite exposed to the elements. Take each of the leads off and dry them as much as possible. A good spray of WD40 will help.
Does the engine run roughly or is it still operating as normal? The system is obviously detecting something is amiss, but it may just require a reset. This is done by leaving the battery disconnected for over 45 minutes. When you reconnect, just start the engine and leave on ide (i.e. dont rev it) for a few minutes and the positional sensors will retunr to default.
Nige
Fiat Punto JTD
Fiat Barchetta
http://www.angeltuning.co.uk
http://www.bravo-guide.co.uk THE Fiat Bravo site