I noticed this week that the temp gage in my 2006 300C wasn't working. I even installed a new temp sending unit without any luck. There seemed to be only one thing left to do but I wasn't about to go to that expense and that was to install a new instrument cluster.After trying all the suggestions in the forum I finally found the problem. What I found wasn't talked about in any of the discussions I found. There wasn't a good ground on one of the wires coming off the sending unit. I hope this helps someone with a similar problem. I spent about (3) days off and on till I located this problem