murphy wrote:
The fact that there is no honeycomb in the primary, and there are also no catalyst codes makes me think it could be the O2 sensors. Not sure if it would be the upstream or downstream ones. Downstream would be my uneducated guess.
It’s also not a good sign that the honeycomb is missing. Generally it gets sucked into the cylinders during the EGR process. A compression test may be a good idea.
It seems improbable that 10k miles would completely gut a CAT unless something else is significantly wrong. Like dumping raw fuel into the exhaust.
Any chance the ‘mechanic’ just busted out the honeycomb and sent you on your way? Could he have covered his tracks by reprogramming the ECU, removing the CEL from triggering? Seems like I’m cooking up a pretty solid conspiracy theory. Maybe someone with more automotive experience could correct me.
The one that's missing the honeycomb is the upstream cat. The one that was replaced was the downstream. It's possible ye broke out the upstream catalyst, but it's also possible that's what clogged the downstream one in the first place after 200k miles. It is getting g a catalyst efficiency code as well, but I know about that already which prompted me to get cats and do the rest of them.
In this case I don't think the rough running is part of the cats, but I'm still plugging along.
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