At our shop with every transmission service we include the price to replace the A/T Plug Adapter. This Plug Adapter is for the wiring harness to plug into the electronic guts of your Mercedes Transmission. When the plug is not replaced and begin to leak more through the worn out seal and ends up getting soaked in Transmission fluid, we can see problems happens as this video demonstrates that Transmission fluid can eventually travel up through the wiring harness and into your transmission control module. The module will get soaked in the fluid and cause transmission problems. This is why adding the extra cost for the adapter plug as part of your AT service can save you money and headache in the long run as we do our best to make sure your Mercedes-Benz keeps you happy.