just wanted to let everyone know that I scanned my car with my otc 2000 monitor and up came code 91. I went to autozone and they gave me a print out of the possibilities (2 pages long) Well, I changed the driver's side o2 sensor, cleared the codes, and no more check engine light!! Oh, and I changed the pass side 02 as well, I'm not sure if this was needed, but why not start off with both of them being new.