Well, to be fair, how long did you spend researching the forum, deciding what to try, ordering the part, etc? Then after factoring that time in, how much extensive Mercedes training have you had to solve the problem if it hadn't been so easy? Note that if it had NOT been the sensor, whatever time at the dealer spent getting the part from stock, replacing it, then testing, then pulling the part back out to find the real problem - well, just a waste of time. They too will do an extensive diagnostic before the actual repair.

In short, this forum has saved you a lot of time and money - but that doesn't make the dealer underhanded. It just means you have the time and ability to take advantage of other choices.

Steve