I've done this before so I know what to do and they radio presets etc. will die, but what about the currently stored DTC codes? Will they be erased? Can't get to the dealer till Monday and I don't want to waste their/my time doing work on the check engine issue I have.

 

I would use a 12 V DC power supply to maintain the voltage, while swapping the battery. This way your radio stations stay programmed. DTC codes must be cleared by an OBD II tool. The codes are like files in your hard drive, unpowering does not erase them.

 

Thanks - what I expected. I might just wait anyway... gotta see about powering during the swap although reprogramming the stations is not a big deal.