There are a lot of phones out on the market, and most of them work very well with Dash. However, certain phones and OBD adapters don't play well together, and it can sometimes be difficult to figure out what's going wrong.
Luckily, it's usually not hard to get things connected up and working once again. Often, the phone and OBD connector have just lost their connection momentarily; just toggle Bluetooth off and back on.
If that doesn't take care of the problem, check that the phone hasn't lost its pairing with the OBD adapter. If that's happened, it's a good idea to pull and then re-seat the adapter; after that, go through the pairing process once again.
If that doesn't take care of the issue, it's time to get in touch. Send us an email to email@example.com and describe the issue for us. We also want your log files: you can send those to us within the Dash app by going to Settings -> Send Feedback.