If you have a problem with immobilizer and the Red Key, there is a 'cheap' solution; Fuel pump modification!! The way the immobilizer works is stops the fuel cut off solenoid from operating if the key box doesn't recognise the key.
On the fuel pump is a lump with 3 wires going to it
This was posted on the Fiat forums.
'hi new member ,(joined last year first time iv written) iv bypassed many of these code systems .3 pin plug going to code control unit @ rear of pump unplug - smash of control unit (dont damage solinoid behind control unit) need to remove 2x shear bolts that secure control unit use vice grips once removed check which wire @ 3pin plug you disconected is the ignition supply (sure its middle) solder to the wire on top of solinoid , tape up 2 exposed wires left over , now disconect ( large plug on code box next to steering coloum yellow-green or black in colour depending on year produced this stopes code light from coming on) van shall now start but you dont have an imobbilizer , dont pay any more than £200 for this to be done thats what i charge thats my knowllage included in that well now iv told you all you can save loads and do it yourself good luck .......'
Also.........
'Ah yes Simon, I have bypassed my pump. Only the other day as became unreliable again.
Just a note though, it did not involve smashing anything off, just pryed off the lid. The circuit board is mounted in silicon so scrapped it off and cut the middle wire and soldered in a piece to the soleniod. Re set the board in neutral cure silicon and popped the lid back. Now 100%
Only thing I wished I had done, Not cut the middle wire just bared the insulation and soldered the new wire to it. I have a feeling this would prevent the code light comming on.
Ah well next time.'
If you remove the Yellow Code Box by the steering Column then code light doesn't come on.
Incidently - this 'cure cost me £75 from a Commercial Vehicle repairer who was very familiar with this issue!!!!!
Simon