I am recently the lucky owner of an '06 E55. The oil change was done right before purchase but I want to check it. I cannot seem to though. No matter when I attempt to check it, I get the "observe waiting period". Even if I go out to the garage 1st thing in the AM. I checked the manual and I seem to be following the instructions. Any thoughts?

 

Weird. Typically I can check within one minute or so after turning the engine off. (I know my answer didn't help, sorry!)

Although, I DID just change my oil level sensor with my last oil change. It was super wonky, some days being fine, other days displaying the bright red "stop car" low oil light. Added an additional 4 minutes to the oil change procedure to also swap the sensor.

 

I have had exact same problem. the car can sit for 24 hours and still give you "observe waiting period" message. Then it gave my error "check oil and visit workshop". After than it gave me "stop the car, oil to low" in red. After all those annoying messages I finally changed the sensor and problem was solved.
I think your sensor is going bad.

Thank You,
Arseniy Sumskoy.

 

change the sensor

 

+1