Thanks again.
However I never asked the AA or Vauxhall for the fault code.
Looking back I wished I had, but I didn't even think about it !
I think it "might" be around the gearbox as it only happen'd when put under presure at speak, over 65mph !
Gearbox oil has been checked and is topped up and clean.
Must be some kind of ECU or EGR valve, whatever they are !
Obviously not a mechanic and unable to do any work myself due to a few mobility issues.
What I might just have to do is wait until it does it again, stop and call the AA and this time ask them for the code so I can do my own research on what it may be.
Have checked all over the internet, and this forum and it could be loads of things, just have to pin point what issue I have.
Just hope it does not do it next when I am towing the caravan !
Again, thanks for your reply.
Kind regards
Brian