The reason why is your nexus 7 has lollipop on it. I’ve copied the instructions below from the admin on this site. I’m not sure how many this has worked for but I’ve tried numerous times the steps listed below and it won’t work. I even did a factory reset and still did not work. Good luck to you and please post your results.

PostRe: Torque not working with Lollipop
on: December 9, 2014 (GMT) Quote
Hi!
It’s working with Android 5 as it’s been tested quite a lot with it!
If you upgraded and it’s stopped working, then do the following as you may have suffered from an issue during the upgrade (linked to the bluetooth radio used in some of the clone adapters):
* Go into the OS bluetooth settings, and delete the bluetooth OBD2 device
* Reboot the phone (this is important!!)
* Re-pair the OBD2 device with the phone in the bluetooth settings
* Start torque, do into the app settings and re-select the OBD2 adapter (even if it is already selected)
* Quit and restart torque (to speed up reconnecting if you don’t want to wait a short moment) and you should be up and running.
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* Alternatively you may just need to re-select the adapter in the app settings without re-pairing it in android. You can do this in the main app settings (and don’t forget the vehicle profile if you’ve overridden it there)
The only other thing that would stop it connecting are other apps already connected to the adapter, or not disconnecting from it properly when they quit (this will then stop Torque from connecting as the OBD2 adapters only allow one connection at a time from any app)

ok … i have tested !

but
torque found adaptator AA:BB:CC:11:22:33

and no connecting …

Sounds like you might be in the same boat as me, however I was getting a proper mac address. I talked to my provider Verizon and they say there will be a lollipop update at end of month that addresses bluetooth issues.

I have tested that :

Go to Settings > Bluetooth on your Android device, touch the settings icon next to it, and then Unpair it. Reboot the phone and try again.
If you still can’t connect, then delete the profile on both devices again. Afterward, go to Settings > Apps > All > Bluetooth Share and Clear data and Clear cache. Restart the phone, and set the connection up from scratch.

it worked once !!

ODB Car Doctor
EOBD facile
Dash command

all are lite version : They are OK on lillopop !!!