My ODB-II (ELM327) device has the default PIN of 1234. Is it possible to change this PIN? And how?
Make cable to the device with an on/off switch in the +12v line - if it does not get power it won’t work - just remember to turn it off when you finish .
You could also use an ignition controlled relay to do the same so it comes on with the engine but will be off when you stop.