Hi, I have a 2009 audi TT, 2 weeks ago , it got an error code P 2181. The meddle acted strangely, up and down and sometimes it stayed at cold. I looked thru the forum and tried to replace the coolant temp sensor. Well , it worked for a week, everything seemed normal, then 2 days ago, the error code came back, and the temp meddle now stayed at cold all the time. Do you think I have problem with the thermostat? I appreciate all your help!. Sorry I posted one yesterday and I did not say it clearly.