Hey there M3Post,
I have been looking around the forums for an answer to a specific question but I cannot seem to find the resolution. Hopefully the community can lend a hand
I have a E93 M3 and I have removed the muffler to get the beautiful sound of the V8. I love it. However, I have recently come across an O2 sensor fault code. The dealership says they cannot replace the O2 sensors because the muffler delete voids the warranty on the exhaust system. However, I read online and was told from some friends that under the Magnuson Moss Warranty Act of 1975, 15 USC, 2302 and Clean Air Act 42 of USA code 7541, that in order for the dealer/manufacturer to deny a warranty on a claimed part, they must PROVE that the part I installed/had installed DIRECTLY caused the failure of the part on which I am claiming the warranty.
They did not prove anything. And after doing some more research, I found that not a lot of stuff exists on whether a muffler delete would damage the O2 sensors because it logically makes sense that it has no effect, but nobody is going to bother to test it.
I then tried to research California smog/emissions guidelines, we all know they're super strict about anything that might affect emissions systems, and the O2 sensor is part of the emissions systems. If mufflers affected O2 sensors you'd be damned sure they'd mention it during a smog inspection.
As of now this is the ammo I have acquired to fight the stealership but I wanted to see if anybody else has more specific information that could help me get the O2 sensors done without having to put the muffler back on.
Cheers!