Having exhausted all ideas I have to try and start my Multi I can only think the immobiliser is preventing the car from starting, is there a way to reset it? Also, is there a fuel cutoff switch on the Multipla (mine is a 2001 petrol 1.6 ELX model)?
One more thing,
I had a Fiat Coupe which didn't start because of the anti-theft. I could hear the starter motor going strong but the engine didn't even try to fire up some fuel.
If the code is acknowledged warning light (picture of key with the text code below) the instrument
panel will flash briefly; the code system has acknowledged the key code
and deactivates the engine immobiliser.
Well I thought I would post just to report what the problem turned out to be. Having paid an auto electrician to come and look at my Multipla, it turned out to be the fuel inertia cutoff switch faulty and once remedied, the car started no problem. Thanks Joipalli for your help.