intermittent non-starting problem

With the 'start prevented' message being displayed it will be a fault with the transponder communication from the ignition key to the immobiliser. Have you any other transponder devices on your keys or in the vehicle? Have you tried different keys to see if it is a fault with just one key? You didnt say what year your S80 was however there is a software update available for certain model years (dealer only job). Possible fault with antenna around ignition barrel. Possible fault with antenna wiring back to central electronic module (the immobilizer is in there). Possible fault with central electronic module. Possible fault with wiring to central electronic module. The best thing to do is first make sure you have no other transponder devices on your keys or in the vehicle then try different keys. If the fault still persists with different keys take your car to a main dealer as they are the only people who are going to be able to resolve the issue. Tell them you have no othere transponder devices in the vehicle and you have tried different keys.

Thanks very much for your help - will take this info first to a friend to see if he can check anything on your list of suggestions (I've already checked for other transponder devices) before I then take it to a dealership. I'm assuming this will probably be quite costly ??? ! ?? Thanks again for your advice. Regards.

Did you ever find out what the fix was for this issue? My 2000 S80 is having the exact same problem now. Thanks.