A multimeter is a horrible way to track O2 sensor activity. I handheld or device based analyzer that scopes it or uses data form the pcm to graph there activity gives a way better idea as to what is going on with them. And according to you in your first post here you are implying that the MAF was the suspected cause of the converter failure and now that it is replaced it would seem to you that it is fixed but you seem to still think that he is running rich when in fact he said the engine was missing but did not give further data as to how or why so are you not yourself trying to say what some of the issue is in the forum yourself? It was never implied to replace the cats without testing them first. It was implied that the the Bosch O2 sensors do get chucked because they have issues with this powertrain such as lack of response speed.
He said he replaced the cats first, then the MAF so I was saying that the time it was run with the faulty MAF could have damaged the new cats... And I'm sure things are a little different in CA. but up here in Vermont with harsh weather and road salt we have a lot of problems with corrosion. Trusting the data at the pcm doesn't always pan out very well. We often have to test sensors at the source to eliminate the chance of corroded connectors or harnesses changing the resistance and there for the values seen at the pcm. And you did imply to replace the cats before testing, it was post #11.. then after he had them tested to be good, you again told him to replace them anyways in post #16...
I had a Dakota in the shop once that had me pulling my hair out with a converter efficiency code, the data on the scanner led us to replace the post cat o2. After replacing the sensor nothing changed, still looked faulty so like you I had a boss who blamed to maker of the new sensor so we changed it again. With the second one installed I tested at the sensor and got good readings, at the pcm connecter still out of spec. I traced the harness along the frame for any connections or splices and found a factory splice inside the wire loom that was soldered but wrapped in tape, it was kind of a cloth tape and moisture had gotten in and the connection was just a ball of green goo.. Repaired that splice and everything was good to go, most likely the origional o2 was still good.
