Hi all, i have a fiat stilo active sport 1.6 2005 and over the last few months it has occasionally lost power temporarily only for a few seconds and could happen any time, fast or low speed. Then recently it has started cutting out randomly but it would always start again no bother straight away. Had diagnostics on it which showed no problem. Then it cut out last week and the immobiliser warning was on and it wouldn't start again until I locked/unlocked the car then opened and closed a door, this happened a few times. After this on a different day i was driving and all my dash warning lights were flashing on and off and gages were going up and down which all stopped after 10 mins of running the car. It ran fine over the next few days But yesterday I went to start it and the immobiliser warning light wont go off this time and it just wont start. Got diagnostics on it again and its coming up with code B1029 serial line but I can't find much info on it, amongst other things like power steering etc. Does anyone have any idea what might be going on? Had the earth strap changed today and cleaned battery connections which has made no difference. The battery has plenty of voltage running through it. Any help/advice would be greatly appreciated!

Check fuses and relays for corrosion on under bonnet fuse box. Pull the fuses out to inspect the fuse legs for corrosion. Un plug the engine ecu to inspect the connection pins for corrosion or water ingress.
Could be an ecu or control unit that has failed or got water in that's shorting the can network.
Check for fault codes in all systems.

Thanks I will try those