I know this is an old post and an even older thread but should someone read this person s questions, I'd have to reply with, "Did you read the first 6 pages of this topic?" Don't be lazy and skip[ to the end. Read read read. Its the only way you are going to learn and get all of the info. Removing the 02 sensor and seeing an improvement in performance does not mean the 02 sensor is bad. You're opening a hole in your exhaust which gives the exhaust gases some place to escape, thus proving that you have a blockage in your exhaust system, which is probably going to be your CC unless someone stuffed a banana up your tailpipe. As far as the Thermostat question, you don't repair a faulty thermostat. You repair the problem by replacing the faulty one with a new one. How does a new thermostat help prevent the CC from getting clogged or eventually blocked? Your engine runs much richer when it runs cool. A rich running engine will cause the CC to clog up. An engine with a stuck OPEN thermostat may not produce a CEL because the computer does not check things like an over-rich condition until the engine reaches normal operating temperature. I would think that you would get a code for the engine not running at proper temp though. And to think I learned all of this just from taking 10 minutes and reading from page 1 to page 7 of this topic. I'm sorry for the sarcasm, I just think it's important for people to do their own research otherwise your just giving them a fish instead of teaching them how to catch their own. Sorry I feel bad now.Hi Jimmyjam, I thought if you removed the O2 sensors and the power returns, it was the O2 sensors? If the stuck open tstat is the causing problem for the cat clog, should you install a new tstat or can that be fixed? I have noticed a slight decrease in acceleration and a change in gas mileage in my 02 TB. I used octane booster and noticed an improvement in my gas mileage, but it's still not right. I also had an oil change using a FRAM High mileage oil filter (since it was put in I have heard bad things about that type of filter); could that be the problem? The oil filter makes the engine sound like a 18 wheeler!
I love this site; am learning a lot about my 02 trailblazer!