Tried a number of searches but can't find the answer to this one. I've given in to curiosity/gimmickry and bought a cheap bluetooth OBD dongle from Amazon to use with Torque Pro. Does anyone know whether the power to the OBD port is cut off when the engine is turned off or whether (a la the 12v socket) it's continuous? The thing hasn't arrived yet so I can't test it out but was just wondering whether anyone else leaves theirs in or has to take it out to avoid a flat battery.

The ports are usually powered continuously, whenever I connect a reader to them the reader always powers up from the port without the ignition on.   The ignition needs to be on to supply power to the controllers so that they can be read.

Oops. I deleted my reply about the ignition needing to be on when using VCDS, the explanation for which is in the informative reply above which answers the original question.

Thanks lads

I've got one for mine, worked excellently but it appears to not work anymore. Probably the cheap low quality dongle lol