I know very little about the coding which is discussed quite a lot and was wondering could you explain to be briefly how it is done? Can you buy the software kit for doing it yourself. Finally as I live in Northern Ireland is there any guys you could recommend.? Cheers

The coding is done through the OBD II connector. The most popular method is called VCDS which requires a special cable made by the US manufacturer Ross-Tech.

The UK distributor is Gendan. Owning the genuine cable entitles you to the software (and updates) needed to access almost every facet of the car's CAN BUS (a vehicle data transmission system actually developed by BMW).

Requirements are the cable and a laptop running Windows (also works with Windows emulation on a Mac).

 

Other much cheaper alternatives exist, like bluetooth OBD II dongles, that allow you to view/change settings, but are much more limited in their scope.

Requirements are the bluetooth dongle and a smartphone or tablet.

 

There are also "pro" level kits available, but these are out of the sensible price range of most home users.

 

There is a forum dedicated to VCDS which includes a list of members with VCDS (2 shown in NI).