Okay so funny story...I spent ALL DAY researching this issue and finally feel comfortable tackling some of the problem...my husband comes into the garage and my five year runs into me...I drop our phone into the engine bay and now the phone is stuck...RINGING INSIDE MY X5!!!! It has been THAT kind of a day...but wait it gets worse...so my husband who is NOT SO PLEASED that the phone is inside the x5...rescues the phone and I start to explain to him what I think the problem with the expansion tank maybe and he grabs the little water hose on top of the expansion tank....yeah you know the one...and as I am saying DON'T TOUCH THAT...I of course hear it SNAP!!! Okay so we ordered the expansion tank, a new water line and a coolant sensor...we figured sooner or later these componenets were going to go bad anyways so why not start with the simple obvious things and work our way up to the big fixes...While my low coolant level light was coming on the interesting thing is the first time I added about 10 ounces of distilled water and the second time I added about 6 ounces...would the loss of this small amount of coolant trigger the low coolant level light??? Looks like I am stuck waiting for parts for the next few days, but I am plan to keep reading so I hope you all will keep making suggestions...THANKS SOOOOOOO MUCH!!!