I took my downpipe off yesterday to fix some issues with it, and when I took the oxygen sensor off, the little metal "casing", for lack of a better term, that goes around the actual sensor part itself that sticks into the exhaust stream, came off! The reason was because there was some jagged metal inside the pipe where the hole was cut to attach the sensor. I talked to one of my good friends about it, and he said it was probably bad, but nobody had one in stock, so I reused it. The car seemed to run fine, so I'm wondering if anybody knows or has an opinion of how soon it should be replaced. Normally I would just order a new one, but I'm broke at the moment!