Ok, I have just done this to my mk2 ph2.
It IS a straight swop.
Battery should be disconnected for about 15mins to be safe. My 172 airbag fitted right for the car, so I dont see how any others should be different - but always check I guess.
There is clips at back of wheel to unclip the bag container. You can rotate the wheel to access these but they can be a little hard work as they tend to enjoy clipping back in when youre doing the other one!! make sure wheel is straight again when youre done this.
Now, pull the front (horn bit) away and this should be attached to the airbag part. undo the top and bottom wiring from the airbag (they have little clips you need to undo before you pull these off)
Then undo the bolt at the back with a torx screw, dont take it compltely out just undo it enough for you to be able to pull the wheel away from the column. Undo the wiring connector for the horn which is attached at the back of the empty compartment towards the top.
Now completely take out the bolt and pull the wheel free. youll notice the hole is goes into has teeth. This ensures the new wheel will fit exacltly in the same position (hopefully).
Basically do all this in reverse to attach the new wheel. Haynes tell you to buy a new bolt when reattaching a wheel but neither me nor J3ned saw any point in this
Hope this helps
