wondering if any of you have seen this before?i have a 99 accord 4cyl vtech.recently replaced o2 sensors cleaned out intake plenum and replaced cat with aftermarket.couldnt afford the factory one!problem is still getting code showing threshold deficiency dealer service advisor says aftermarket cat isnt as efficient as factory ones so even though it might be operating fine at say 85% efficiency computer is used to seeing 90 or 95% therefor throwing the codethink its p0420.heard their is a sensor that can trick computer into thinking cat is performing better?has anyone heard of this or am i destined to shelling out 900bucks for honda cat?got car to pass emissions so im gud for next 2yrs but chek eng light is bothersome.never know whats really going on.car has over 216,000 miles n runs like a champ but just want to get rid of that light!any help will be greatly appreciated!

 

I've moved this to General Tech.

 

After the work, did thery clear the old codes. Just trying to see if the P0420 is left over or is soming back.

Some will trick the secondary o2 by adding one of those old spark plug non-foulers.

 

Plus you will also need to verify no leaks in the exhaust system as this can cause bad readings from the O2's.

 

thanks for your response.yeah they cleared the codes several times and they keep popping up again.light is constantly on now.they said they checked for leaks thru system.mite have to have it rechecked just to make sure.as far as the spark plug fowler can i pick that up anywhere?how about would i go getting it installed into system?

 

Sorry, I'm not a fan of "tricking" systems,,,you can hide real problems. I know how to do it but will not post it....not the right way to do things.

Sounds like a "shop" is doing this - they should be on the hook. If they say "x" is the issue then you pay for that and it is not....get your money back and find another shop.

 

appreciate the help.guess i will have to start saving for the 900bucks the dealer wants for a factory cat on a honda thats worth 4gs.lol.appreciate your advice thanks again

 

There are plenty of members that have replaced the cat with aftermarket ones and not had any issues.

What brand was used when you replaced it?

The fouler is used to move the secondary O2 out of the direct exhaust flow....google will come up with all kinds of things.

The OE converter is ~$550 (online dealers - Majestic Honda) and there are places that will pay for your old converter....depends but some have gotten ~$150 for the old one.

 

thats probably guna be my best bet.they hit for 350installed on aftermarket.and seem clueless on how to get rid of chk eng light.dealer said best bet is getting fact cat.hey i appreciate your advice hopefully i can get that 150 to put towards the 550.guna have to extend the pipe now that they cut to fit old one.by the way what replacement struts you recommend 216k on car and never replaced them!

 

More to the story. If the "shop" cut and spliced in a cat and didn't get the placement of the rear O2 correct.......you will get a code. I'm old, stupid and know nothing....but the "placement" of the rear O2 is key to getting a proper reading from it. Just my opinion.

Again, several people have replaced cats with aftermarket ones with NO issues. You can go OE or get a quality direct fit converter, new rear O2 and go from there.

Struts.....a debate....I'm a fan of KYB but that is just my opinion.