viewer. I didn't bother to connect it though as I was sure the car would pass. I figured with no CEL and with all the readiness monitors set to complete -- I didn't even bother to confirm this before the test as I had checked often enough in the past to have a high degree of confidence they were set to complete this time -- it would be an in and out done thing.
The converters do shed their outer grains of catalytic metal over time. But my belief is the stock converters have a good "heavy" layer of these metals and a large surface are and can tolerate this loss. I note the converters on my car have now covered over 279K miles and both work just fine, albeit one side occasionally triggers a P0430 error which does suggest it is wearing out. (It also could arise from a loose converter "brick" that shifts position slightly and as a result the exhaust gas flow through the shifted and out of place converter is not optimum.) The problem converter has never been off the car, well, not since at 25K miles when both were removed to replace the RMS, so I have not had a chance to give the exhaust manifold with the suspected bad/loose converter a shake to test for a loose converter.
A "killer" of converters is ZDDP. The phosphate in this additive leaves a layer of deposits on the working surfaces of the converter and effectively renders an otherwise good converter bad. This is why I inwardly cringe when someone elects to run an oil with a large amount of ZDDP in it with the mistaken belief this will prolong the engine's life. Zinc is an anti-scuff additive and even Mobil 1 0w-40 has IIRC 1000 (or 1100) PPM of this stuff, but without the phosphate. There is the risk to the converters, but there is really no benefit to engine life and in fact there is some risk of shortening engine life. Large amounts of ZDDP, the phosphate in it, besides being harmful to the converters also contribute to oil break down at the ring/cylinder interface at high RPMs (my references indicate this can happen at over 6K RPMs) which can actually work to shorten the engine's life.
I second that dismantler's idea. I was prepared to source a pair of converters from Parts Heaven in Hayward and have the tech swap them with the ones on the car in the hopes the "new" converters would do the trick. At some point I considered a new converter for the suspected bad one but at this stage I think installing a new converter with an old converter on the other bank would result in an engine fueling imbalance of some sort. Thus I would drawn to replacing both converters, and possible all 4 O2 sensors, at the same time. But factory converters are very expensive, on the order of $1000 or more per part. Toss in the cost of new sensors and the labor and ouch!
Anyhow, the car passed its emissions test but I can't help but wonder a little bit what this failure will bring with it next time? I wonder will the car have to be retested a year from now, or will the DMV let it go two years as before? Will it have to be tested at a Star station again, or will just the plain test station suffice?
Oh, the tech made a half hearted inspection of the car's exhaust system from behind the car and down low. There was no lift to put the car in the air. In fact the tech didn't even expose the engine compartment to confirm the engine was stock at least on top. (It is stock through and through though.)