My MX went through a phase where it kept complaining about a passcode. I can't remember exactly what caused it, but I think it's because another device was in range that was paired with the MX.
What I did was make sure that no other phones/tablets that have been used with the OBDLink are nearby with Bluetooth turned on. I also removed the OBDLink from these devices. Make sure no other apps are trying to connect with a bluetooth device (Pebble watch for instance, also any bluetooth headsets/headphones). Finally, I left the OBDLink unplugged for about a minute or so, removed the OBDLink from my primary device, plugged the OBDLink back in, and re-paired the MX to the device (my head unit in this case). It's been working good ever since.
As a quick fix, turn off bluetooth on any phones or tablets in the car, delete the OBDLink from the device you run CaniOn on, press the button on the OBDLink and re-pair your CaniOn device.
If it's still giving you trouble after this, I'd try to do a warranty claim on it and see if you can get another LX or possibly a Bluetooth MX.