2005 Honda CRV. This is my son’s car, and I don’t have precise date / mileage details. But the gist of things should suffice.
I helped him find/buy this car used back in spring '21. It had something like 160K on it, but in excellent shape. Original owner, always serviced by Honda on schedule, with the stack of receipts to prove it. (Owner’s brother was also a detailer, so it looked amazing inside and out). He doesn’t take it to Honda, but does keep up with the normal maintenance schedule.
About a year and a half in he ended up with a clogged cat. That’s when he found the old Honda receipt from 2019 where the prior owner had it replaced - presumably with OEM as it was done at a dealer.
So I asked him coolant or oil loss, and MPGs. And he never has to add coolant or oil (between changes). And his MPGs are right around 23 which is 100% in line with EPA est. and fuelly self-reports.
He’s now got it throwing a P0420. (And I know this is where people will be wondering about mileages between these events, but lets just say without coolant/oil loss and with normal MPGs - not enough!)
The cat he had installed was by a small town, independent shop. Probably not OEM, but I don’t know. But in my mind that wouldn’t explain anything if two Honda cats failed.
So anyway…what else do we got? Without normal explanations for contaminated cats I’m at a loss.
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It could be a faulty oxygen sensor. were they replaced with the cat?
I don’t know about the O2s. (He’s with me in VA right now - the car and the records are in NY, and the latest P0420 was new news to me yesterday).
He’s got a basic scantool, and I told him to record live data on the O2s and send me the file.
If the dealer replaced the cat in 2019 on a 2005 car, it is likely not an OEM cat but an aftermarket unit. Why? Because carmakers only support parts for older cars for 10 years.
If this car doesn’t live in one of the California-emissions-like states, it likely got the cheaper aftermarket cat.
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Fair enough. But aftermarket or not, something wrecked the OEM. Something then clogged the dealer installed cat #2 in reasonably short order. And now the P0420 in reasonably short order. The only thing that makes sense, explanation-wise, is that it’s throwing too much junk down the exhaust - coolant, oil, unburned fuel. But there are no signs of that. So I’m still just … well, thinking…
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Does the CRV have (2) catalytic converters? I wasn’t sure.
Also agree that this is probably a “cheap” aftermarket early failure. I’d get another new one installed and move on. Anything else is just speculation.
Does he use fuel additives??
My son for some reason thought they were good for an engine and used to much, if it can cause a coating on valves, it can cause a coating on the catalyst also…
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That surprises me about the fuel additives. Other than the slime did it somehow result in that valve damage? I’ll bet compression on that cylinder was great!
In any case, he doesn’t use fuel additives.
Is your son able to get a fuel trim test? That seems like the most simple way to start. Is he able to display the engine coolant temp sensor output?
Caused a build up like carbon that broke off and got under the valve as it was closing and pie cut (broke) the valve… The engine had very little if any carbon build up, was regularly shifted above 5K…
It was a good teaching moment for my son on diagnostics as I had him run every kind of test I could think of for the bad miss, OBD1, before I got tired and said run a compression test… lol
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