If you are looking for reliable BT OBD2 interface, then
is a way to go. I have tested this interface with few smartphones and found it very stable solution.
THIS SOFTWARE IS DESIGNED TO READ ECU EXTENDED DIAGNOSTICS INFORMATION REGARDING DPF SATURATION IN OPEL CARS, SPECIALLY OPEL VECTRA CAR POWERED BY DIESEL ENGINES: Z19DTL, Z19DT, Z19DTH USING ELM327 BLUETOOTH DIAGNOSTIC INTERFACE VERSION 1.4b OR NEWER. THIS SOFTWARE MAY DAMAGE YOUR CAR, MAY CAUSE COMMUNICATION PROBLEMS ON INTERNALS CAR CAN BUS OR MAY STOP ENGINE FROM OPERATION OR MAY JUST NOT WORK PROPERLY OR NOT WORK AT ALL. DO NOT USE IT DURING DRIVING OR WHEN ENGINE IS RUNNING, PLEASE USE IT ONLY WHEN IGNITION IS ON AND WHEN ENGINE IS NOT RUNNING. AGAIN THIS SOFTWARE IS DESIGNED ONLY FOR OPEL OPEL CARS, SPECIALLY OPEL VECTRA POWERED BY DIESEL ENGINES: Z19DTL, Z19DT, Z19DTH. THIS SOFTWARE MAY DAMAGE OTHER'S CARS INCLUDING NEWER OR OLDER OPEL CARS.
YOU HAVE TO HAVE ELM327 BLUETOOTH OBD2 DIAGNOSTIC INTERFACE COMPATIBLE WITH 1.4b VERSION SPECIFICATION AND ANDROID SMARTPHONE CAPABLE OF RUNNING THIS APPLICATION AND CAPABLE OF CONNECTING WITH DESCRIBED ELM327 DIAGNOSTIC INTERFACE TO USE IT WITH SUPPORTED CARS.