This is what you need if you fit an aftermarket seat that does not plug into the factory socket. Such as a Recaro, OMP, Sparco, Bride etc. This tricks the car into thinking you have a factory seat with airbag so you do not get the dreaded airbag warning light which disables all your airbags! Uses OEM plug for a perfect fit that won't come loose.
If you are in the US you will also have a rail position sensor and if fitting replacement a passenger seat, an occupancy sensor. You will still get an airbag light if you do not also deal with these!
For the drivers seat you have three options:
1. Remove your harness with rail sensor from original seat, plug into car and lay under the seat. (you may be able to seperate and de-pin the rail sensor from the plug)
2. Buy a replacement harness - the part number is on the harness. I can help you with sourcing one if you like just reach out. It's important to get the correct one for your car.
3. Buy sensor separately and wire it directly to the socket on the car. Purchase the sensor on the site here. If you trace the wires from the sensor on your harness to the plug you should be able to work it out - just follow the wire colours. See picture with brown and blue wires where someone has done it. Note you may have a red socket on a later model car. This is the most difficult option and suitable for someone comfortable with a bit of DIY.
Passenger seat options:
2. Buy a seperate harness, occupancy sensor module and occupancy sensor. reach out to me you if want to go this route.
Installing the plug
Install with the car not turned on and you should not get a light at all. If you do get a light you will need to clear out using VAGCOM or OBDeleven.
To remove factory plug. Slide black part of the plug you should hear a click. Push down on the top of it to release it and pull the plug off. It will be firm, you need to push down firmly on the black part, you should hear/feel something releasing.
Ensure pink bit on the side is pressed in (I press them all in). If it is visible when looking into the plug then it needs to be pressed in as it prevents the plug from being inserted.
Plug will "click" into place. Push/slide the black part down to secure it in place.