(T) Mk2 Punto Died while driving, now won't start

Greetings,

My car is an X reg fiat punto 1.2 with 96000 miles bought second hand October last year.

Had a minor issue in the past with battery draining if not driven for 5-6 days but as driven regular only occured three times before. Went away on hols for a week, when came back as expected battery drained so put on charge overnight and put back in next day.

Car started no problems, drove about 2 miles when engine cut out (all electrics still working fine, windows, lights etc) as I was driving, no action when pushing accelerator pedal.

Tried to restart and engine turns over but does not fire. RAC advised no spark and possible crank sensor failure.

Have got hold of a spare crank sensor and fitted but this did not resolve issue (possible new crank sensor also faulty as from scrapyard??).

Have noticed that code light (little yellow/orange key on dash) comes on and does not go off at all when attempting to start.

Don't think it is fuel cutoff as have located what i think is the switch under passenger side dash and does not do anything when pressed (or even feel like it can be pressed at all to be honest).

From reading forums is this possible ECU/immobiliser fault? would a faulty immobiliser allow me to drive and then suddenly cut out like this? Is there any way to positively identify if this is the issue?

I have only 1 key as that was all that I got and don't have the code card either.

I only paid £650 for the car so don't want to break the bank sorting it out...any advice would be appreciated...

Cheers

It sounds like the immobilser is not disabling when it should. Do you have the other key that you can try?

Unfortunately not, when I bought it it only came with 1 key...