I was told that the upstream sensor (I assume between the cat converter and the engine) is the one that is bad.
Dealer wants $225 just to put one in. I think this is the easier one to get to, isn't it. How would I replace the upstream sensor?
Also, I thought the 3.5L had 4 sensors, two before the converter (upstream) and two after (downstream), is that correct?
Where is a good place to get them and what brand?