Car had the solid immobiliser light on dash. It would sometimes turn over for 3 seconds and stop but if you turned the key slowly it wouldn't turn over at all. I was told this was an immobiliser fault by the rac man with my key not being recognised or the ring at the ignition barrel not working. Tried my spare key still no joy so I read a few threads on here and realised its not immobiliser it's something else. I couldn't here the fuel pump priming and saw somebody had wrote on another thread "it's French wiggle the fusses and relays" thought why not did it and it started lol! Well checked my relays and people on here suggest swapping 2 or 3 small black ones,I believe this is the setup on the 172? Correct me if I'm wrong but on my 182 there are 3 brown and 2 big violet iirc the browns where fine but the big 50a violet one was badly corroded. I cleaned it up and it's been ok since going to replace the relay anyway. Would like to thank the other people for their posts as they helped me a lot and I hope this helps someone else aswell. Cheers.