Thanks for that. Yes that is a picture of the scanner I used and I had used it on a GM vehicle in the past. Couldn't see a place for a battery but there seems to be a recharging port in the bottom. Well I think you have all answered my first question: yes, some OBD readers can cause problems so before you plug one in make sure it is the right one. Now for the follow up question: what do I do now? Like a lot of the contributors to this forum (and many other forums for different cars) I am keeping a visit to the local dealer as a last resort for reasons that have been well documented in this forum. I also believe that one of the great values of forums such as this is to aid people who want to know more about these wonderful cars and would like to do much of their own maintenance. Neither of these goals are met by the "keepers of the knowledge", the BMW dealer.