There is more than 1 issue with dmtl systems on the e90. 1 is the pump going bad itself which would be a 2a17 fc. In this instance a lot of the pumps being replaced are found to have water in them shorting out the pump motor. Don't ask me how moisture gets in them. The other popular one 2a15 dmtl minor leak is often caused by the purge valve not sealing properly (and I've also seen faulty dmtl pumps show a leak when there isn't one), then you have the emissions hose that rubs on the a/c line, and will also throw a 2a15 minor leak dmtl fault. I wish I could help with p-codes but I have never dealt with them on BMW.
I do see a lot of gas caps being left loos also. If you have a green cap still, it prob wouldn't hurt to get a blue click style one to replace it with (updated part)