Start with a new OE BMW gas cap.

The original poster's X5 was hit in the rear so who knows with was crushed, broken, and or leaking pressure in all those lines.

I am sure the body shop is now on a "not my list of repairs" process excuse.
The testing is not complicated. Somewhere out there is a repair tree test procedure that shows, what should the Neg pressure be at the pump, at the separator, etc. The question I asked in a earlier posting was does the diagnostic software, people have been buying in the aftermarket, have the "test evap system" procedure or any of the self tests?

New gas cap in February. I have been getting a SES light randomly showing a small leak detected. This is the first time for this error code though.

No leaks I can find under the hood so I am moving to the rear now after seeing this code pop up. OP's issue could have been from impact but I suspect my dmtl pump has failed from age. (05 3.0 10/4)

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