Same here. I have OBDII interface ELM-323. With its original (free) software it works fine always. With SD it works sometimes, but most of the time immideately after start or in couple of minutes saying that can not connect to ELM interface. If I go right away to other software and try it - it's gonna work with no problems. That is strange, may be SD does not reset ELM contorller properly, or loosing communication for some reason.