Well first.. if your cats are toast.. keep an eye out for excessive heat and/or bogging down/loss of power.. your car may die because of it ahead of time. As for any O2 spacers, longer is always better, 90 degree bends are fine. The idea is that not all cars are created equal, and there is no harm in going longer/bigger on those spacers. If you go with the shortest and it doesn't work, then your only solution is to go longer and hope it works. Good luck! (Oh VCM disabling will have nothing to do with your current codes and it's not a magical fix) VCM only changes the coolant temp sensor so that it is not activated.

 

I live in Maryland, and the state will give you a 3 to 5 month extension just for the asking. You'll then be in spring. Ask you MVA.

 

In NYS, a visual inspection of the emissions system is part of the process. One of their websites states: "the emissions control system of your vehicle must be intact, and must not show any evidence of tampering".

Seems to me that O2 Sensor Extenders might be considered "evidence of tampering".

soundquest: You might want to look into that before going through the work/expense.

 

My non VCM Odyssey threw a cat code as well... It's not always VCM!

 

My muzzled 06 EX-L consistently throws a P0420 after a few hours of towing my 5 x 8 utility trailer, even lightly loaded. Park the trailer, drive for a few days (sometimes just hours) and the code clears and CEL goes out. Never comes on until I tow again.

Vehicle passed inspection a couple of months ago, in between the latest 2 instances of the code. My indy mechanic gave me some sage advice: Don't tow just before an inspection. ?

 

Soundquest, next time break up your very long paragraph, as they are hard to read, especially when single spaced.

 

As others have stated if your cats breaking down foulers will not help. Definitely keep an eye on your temp gauge as built up heat will be the first sign.

Other than that I hear the short 1” extenders work like a charm. A neighbor of mine has been running the 1” extenders in his 2012 for over a year. I also managed to talk him into installing a VCM inhibit device several months ago.


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Hi all,
We had the P0420 consistently (every day after a code reset) for the past several months with relatively new (2016 Oxygen Air Fuel sensors - 40K miles of usage and 2017 Oxygen sensors - 30K miles of usage). We are assuming that the sensors are still good. Is this a good assumption?

P0420 indicates the back catalytic converter, correct? Is this the rear primary catalytic converter (18290-RGL-A00)? It seems that most VCM Odyssey caused this P0420? We did not disable VCM until the first 90K miles.

Is there any way to tell if the common catalytic converter (18160-RCA-S00) behind both of the front and rear primary catalytic converters is bad? Any symptoms or code?

The primary OEM catalytic converters are about $470 and the common catalytic converter is about $360. Are there any recommendations for a 3rd party catalytic converters?

We are using a 1-inch extender to stop the code/reset until we replace the rear primary catalytic converter. We recently are having a brief (1 second) drop in RPM (down to 500 RPM) during idle at a stop sign about 20% of the time. Could a bad catalytic converter cause this issue? Current mileage and performance is fine as normal currently

Any feedback or suggestions are appreciated.

Thank you

 

your car is under factory warranty for emissions system, why are you even messing with it? Take it to the dealer.

 

I have an o8 Odyssey that the catalytic check light came on. Couldn't clear code with my code reader so I pulled battery cable, put 2 cans of Seafoam in less than 1/4 tank of gas, found a lonely road an floor boarded it to 120 mph. Haven't seen the light in over 9 months now. I didn't think it could go that fast but it scared the shit out of me. My wife 'puts' one mile to the store and back. I think the ticket would have cost more than new Cat's and labor.

 

We will try seafoam as an additive, but not getting Odyssey to over 100mph Thanks

 

Have an unmuzzled 05 EX-L with 360K miles. Started getting occational P420 codes at 280K which got progressively worse until I added an extender at 320K miles. Replaced front AFR and rear O2 sensor on rear bank arouund 310K which didn't help. Cat temps have remained stable with no significant loss of power or MPG during the past 80K miles. Denso straight extender; don't recall the length. Easy to drill out. Has passed NY inspection twice (most recently last week) with no issues.

 

Your comment about the NYS inspection got me wondering.

I wonder if a independent mechanic could, from a legal perspective, add extenders and then inspect the vehicle. By "legal" I mean keep his inspection license if it was discovered that he altered the emission system in order to get the vehicle to pass.

Assuming the extenders are considered an alteration (are they?) I see less of a penalty if the mechanic claimed that he missed them during his visual inspection vs. actually installing them prior to performing the inspection.

 

Anyone considering decarbonization might consider my experience with this on a honda passport 7 years ago as detailed in this thread in an isuzu forum.
Water injection
I am not sure how this would help in this particular situation, but it is clearly IMO the best way to decarbonize an engine.