OK...there have been lots of posts on O2 codes and my 2000S Just had the 4th replaced this last weekend. Its good that you cleared the codes. If they return like mine did, you either have a bad O2 or MAF from my experiences. Start with the O2 sensors and test as MNBoxster has described in an earlier thread. Find the bad one and replace it. Chances are that withen 2 weeks of replacing one you will get another code because the others are much older and can't keep the computer happy. Result...you will end up replacing all 4 sooner than later.
How many miles do you have? I had 53,000 and all previous threads noted the O2 sensors will last approx. 60,000 miles. So I was in the ballpark for replacing mine. My MAF also went out. This also set O2 codes but the dealership figured it was the MAF initially due to the fact that I had a terrible idle on cold starting and rough idle throughout my drive. Further tests proved it was the MAF. The O2 will run you approx. 200 each and the MAF could be 300 depending on where you buy your parts. Replace them yourself and save big money on easy labor!
