I will give that a go tonight TazzyK thanks. Well I got the relay today and popped it in, but unfortunately no change, still got both lights on
To give a full update, when the lights first started to show, they would flick on so quickly that I wasn't sure that they had come on at all. After a couple of days, they eventually came on whilst driving but would only be on 50% of the time (there was no pattern as to when they came on whilst driving). On starting the car the lights would be out but would usually come on within 2 mins of starting up. Now, on switching on the ignition (but not even starting the engine) all the normal warning lights come on, but eventually go out as they should, however the Serv and injection lights come on, as normal, briefly flash off for say 0.5 second and come straight back on, and stay on all the time
It seems as though last week, whatever is causing it, was slowly failing, but now has totally failed. Maybe the fact that the engine does not even have to be running for the system to decide that there is a fault means something to somebody, I don't know, to me that must rule out a few of the components in the loop?
Any other ideas would be most appreciated before I eventually resign myself to having to put it in the garage to get sorted.