How do you change the PRE-CAT o2 sensor on a 96 c280. It's at a weird angle. Do you have to drop the exhaust to get to it? If so, what's the procedure to drop the exhaust? I've gotten what I think is the transmission mount disconnected from the exhaust. Where do I go from there? Thanks!

I'm not familiar with the car but if it's tight like the V8s you're going to need a special tool - it's like an open sided socket, sort of a cross between a crow's foot and a socket. It's a special MB tool - about $35. Someone posted a picture of it once in a prior thread, with a part number. You might be able to find it with a search. It's 22 mm as I recall. Snap On also sells one but about the same price and probably special order either way. But I'm pretty much guessing here - there may be a better way to get at it.