Just read this on the website of a company who sell OBD port immobilisation. Maybe a little bias as theyre trying to sell something BUT it does all make sense.
Moving the OBD port seems like a good idea at first due to the amount of car thieves knowing the location for each vehicle. and car forums suggest this as the cheapest method to stop your car getting stolen. Sadly this is not the case the OBD port normally has a very restricted harness length ( around 4-5 inches ) meaning if you do remove the port and plug in an extension lead to relocate it the thieves will still know the original port won't be far from the original location point.
This method is common on the Ford ST owners forum, sadly this has caused more problems than it has solved, when taking the vehicle into Ford's for diagnostics or a software upgrade they will refuse to work on the vehicle, if the OBD port is not in it's original location fully working. This is understandable due to some people modifying the looms so the live and negative are round the wrong way in hope it will damage a key cloning OBD machine.
Tape it up and tuck it away after connecting the extension. No car thief is gonna spend the time trying to sort out and unpick the wiring while risking getting caught, unless they are specifically targeting your vehicle for a reason... and if that’s the case then nothing will stop them.
another idea, buy said extension cable and cut it in two, cross over the wiring and then re-pin your obd port to match meaning that unless you connect the extension between the car and your diagnostic tool you are unable to talk to the car.
another idea, connect an on / off switch to the 12v of the port and run / locate someone in the car creating a kill switch for the port.
any scumbag who is good at their “job” would come armed with fuses, and various other helpful items.