2011 GLK, 25000 miles

Just recentely I recieved a check engine light. I put my scanner on it, and I have a shotty thermostat.

Any others with this isssue? I can only assume that it's a common problem. Doesn't look like to big of a job. Looks like a removal of belt, air pump there on top, and I should be able to access the bolts holding the housing.

Can I drain my fluid without making a total mess is my main concern.

Any folks change one lately? Any insight would be helpful.

 

It is a bit messy. I just did that and all works well after that.