Home FAQ If a crash is detected, should I still dial 911 if I am connected to OnStar via the OnStar Guardian app? Dialing 911 while you’re connected to an OnStar Advisor via the Guardian app may result in two calls being placed to 911 at the same time. This could cause confusion or a delayed response. Previous How will I know that Mobile Crash Response has been activated if I’ve been involved in a crash? Next What do I do if I'm involved in a crash and the OnStar Guardian app isn't connecting to an OnStar Advisor?