Central locking help
It's pretty common. I've had to do 4 in the past 2 weeks. 2 204's, 1 163, and 1 218.
That plate is there to hold in pressure in case of side impact so it can set off the pressure sensors to deploy the air bag.
If you don't know how to rivet or have all the tools to complete the task, I suggest just taking it to your closest dealership. It'll be covered by warranty, assuming you're still in warranty...



