[adhrp]

I am also wondering what coolant expansion tank replacement means. This hose is coming out of the reservoir on the top right driver's side. Is that the 'expansion tank'? If so, this same dealer replaced the expansion tank 10 months ago, which means this hose should also have been replaced, correct?

Because the M550i has two coolant reservoirs, I am confused about which one constitutes the 'expansion tank'. However, it seems only one tank pops a warning when low, and that's the one in the back. I had the same low coolant warning when the expansion tank was leaking 10 months ago, so logic says that that's the expansion tank that was replaced. Someone please correct me if I'm wrong.