hi there im new and ive just open a part time garage, ive got a bmw x5 on a 53 reg its a 3.0i petrol with twin vanos we put it on code readed and took all the codes off service one and other faults, basically we did a full service and few other parts started it was fine no engine management light or any other lights, took it for a run and then let it ticking over fine, but then came to switch it back on and the engine management light came back on so code scanned it again and it came up with 1-6 misfiring and both o2 sensors but i have heared that it can be down to the vanos's and wondered if it would be that plus there is also a rattle that i have also seen that could be down to the vanos seals gone

any help would be good