Discussion Starter · #1 ·
Planning on diving in and attempting some repairs on 2006 9-5 (including a/c compressor, big thanks to all those responding to that post) and replacing o2 sensors will be one of those jobs. Looks pretty simple to remove both "upstream" and "downstream". Which one is which by the way? They are inexpensive enough to just replace both at one time. I'm doing this on a hunch. I have all the issues I understand are associated with sensors going bad. Idle is slightly rough, but smooths out immediately when accelerating. Starts right up easily too. But even more of an issue is it's running very rich, and fuel mileage has sunk. Smell is very strong. I'm hoping replacing may solve the problem. Which sensor is likely the problem? Is removal simple? That is, will they unscrew easily enough? Anything to look out for? Very soon, I need to pass a smog test, and I don't think it would pass as is. It would be hit or miss.