When there is a hex code like that, then there is no code to research. The emulator can be buggy. When I've had a defective brake light switch, it also gives me a hex code but if I used an aftermarket scanner then it will give me the correct code for a defective brake light switch.

I don't think an aftermarket scanner can scan that specific module since it is Crossfire specific, the SLK 320 does not have that module to disable the passenger airbag.

Look at the side of the passenger dashboard and removed the side covering. See if you actually have the module there or if it is disconnected. It is where you can put in a key to enable or disable the passenger air bag.

Have your tried to clear the dtc to see what happens?

Worst case you should be able to find that module on eBay and it is easily changed since you don't have to tear apart the entire dashboard.