Hi Dave, Good post, could do with more like that to educate boso's like me!

As George said "my tuppence worth is that it could just be the knackered cat making it keep dropping out"
I think if we had a flow chart of the programming on an ecu we would know or be able to work out why it drops out. You know how a simple program for a kettle would ask - has the kettle got water in? yes = turn it on, no = do not turn it on and store a pending code. Then it would go back to the beginning and ask the first question again etc until it had three pending codes then flag a fault, could this be happening with the ecu? The trouble with a lot of these things now is they all have little quirks that we don't know about until somebody like yourself puts the time and effort into investigating why, because the manufacturers will not release info to help us.

I don't post that often because by the time I've thought about it, checked on what I am saying and got enough confidence to post without looking a fool - somebody else has already done it. It is reading posts like yours that is slowly building up my confidence in what I am thinking and diagnosing. All the best.

Graham