I got a notification from Nissan that the ECM is defective in "certain 2004 - 2006" Titans. They say it will be replaced at no charge a safety item- vehicle could stop at any time on the road. I haven't seen many comments on this board,so I am wondering how serious this is ? Are there any symptoms ? They already replaced the IPDM; I guess there is no connection. ( I have 107 000 miles- they don't mention miles).