Hi. I am trying to do a bluetooth car. I wanted my arduino uno to send a message to my phone if it is already connected. I am doing some troubleshooting right now, I am still trying to look if my Mit app inventor program is correct.
Please download and post each of those event block(s)/procedures here ...
We also need to see your sketch from the other side, and what messages you are sending, and whether or not you are sending Line Feeds at the ends of messages.