I have an Eonon 9850 head unit running Android 9.0. in a 2003 BMW 330Xi (US).
Bought BAFX Bluetooth OBD2 adapter after the little clear Chinese ELM one was unstable.
Torque Pro connects fine at startup, but if I stop and shut off the car for a short period of time (refueling, go to a grocery store, etc.), Torque Pro will look for a connection for a bit, ‘Checking proto ISO9141 – 2 5 baud’then say something to the effect of:
“No response from ECU. Check correct adapter is selected”, then suggest that I check adapter or reboot unit.
If I take a paperclip and restart the head unit, all is fine, until I switch off the ignition again. It works fine if the car is off for an extended period, such as overnight.
I have tried enabling/disabling anything and everything in the app settings and the head unit setting that I could think of over the past 2 weeks. Set head unit to ‘auto sleep’, also tried ‘shut down after 30 seconds’, and after one hour. No luck.
No Bluetooth device is selected as of now. I had the paired OBD2 checked, but left it unchecked when I uninstalled and reinstalled Torque Pro for about the 5th time, since uninstalling is the only way that I see to uncheck it.
Any advice would be appreciated.

Thanks for the quick response.
I’m OK with tech, but I admit that I don’t know what you’re talking about.
I do not recall seeing a screen about selecting a protocol, and was under the impression that Torque did not absolutely require a vehicle profile, although I did enter as much info about my car as I could such as weight, engine, transmission, etc.
I’ll check into that.
I’m curious as to why it finds everything fine on initial startup – pretty much instantly get “Connected to ECU OK” – but can’t do the same after a quick shutdown. I don’t know whether it’s the app or the head unit software.

EDIT:

I did find the protocol settings, and tried “automatic”, “fast Automatic” and ‘ISO9141 – 2 5 baud’. Same results for all three; connects fine after a reboot of head unit, but ‘no response’ if I shut the car off for 30 seconds and restart.. Reboot unit, and all is fine again.
If it matters, All works fine in the phone, it’s just the head unit with the screwy connection thing.
There is a blue ‘OBD’ icon lit on the unit, so I think the unit knows that the adapter is there, but Torque gets lost somehow.

Thank you very much for the tips.
I tried “ISO9141 – 2 5 baud”, which was what was connecting, and just for kicks, I tried all the others as well.
I have put it back to the ‘ISO9141 – 2 5 baud’ and will keep looking at the head unit for what might be causing this.