I posted a few days ago because my'97 E420was surging rpms while it was idling... it still does this but now the check engine light popped on and says to check the engine electronics. So I took it to Schucks to run the codes and it came up with this PO115 engine coolant temperature circuit code. The Schucks guy said it'spretty vague and that it only seems to happen with German cars. I'm hoping that someone else can clue me in on what exactly this code means before I run it into the mechanic tomorrow! Help!!! Thanks!