P0420 Bad Cat - defouler?

[TACORICAN]

My original Cat was bad, the mesh fell apart so I gutted the mesh before the O2 sensor out. The other half remains there. It's due for smog this week so I happened to come across a used Cat from a non ULEV I4 Accord. Are the cats the same? The cat I picked up seems to be in perfect condition, it only had 50K from original car. Right after I installed and drove for about an hour, the CEL came on. Code P0420 - Catalyst System Efficiency Below Threshold (Bank 1). Could it possibly be the cat? someone told me it may take the car time to adjust. So I've reset the CEL and it comes back on after about an hour of driving.
Any suggestions? I've read of the Defouler or getting a new cat which is out of my price range.

 

[HondaLuver83]

My original Cat was bad, the mesh fell apart so I gutted the mesh before the O2 sensor out. The other half remains there. It's due for smog this week so I happened to come across a used Cat from a non ULEV I4 Accord. Are the cats the same? The cat I picked up seems to be in perfect condition, it only had 50K from original car. Right after I installed and drove for about an hour, the CEL came on. Code P0420 - Catalyst System Efficiency Below Threshold (Bank 1). Could it possibly be the cat? someone told me it may take the car time to adjust. So I've reset the CEL and it comes back on after about an hour of driving.
Any suggestions? I've read of the Defouler or getting a new cat which is out of my price range.

www.horsepowerfreaks.com has a defouler. I have been using it for over a year and no check engine lights on at all. But I have a megan racing resonated test pipe too.


Since your car is ULEV the cars ecu is more sensative to smog and other emissions. You would need a specific Catalytic converter for that car, using a non ULEV will cause your car to throw a CEL.


The ECU keeps checking ur emissions levels and it will keep throwing the same code as long as you keep that CAT there. There is no wait time for the ECU to adjust, everything has been programed into the ECU for a ULEV low emission vehicle.

If I were you, I'd just buy a ULEV cat. A defouler might work in combination with that cat but I am not sure because my car is not ULEV. I think I pay like $40 for my defouler on that website......GL

 

[blacknight]

Be aware though
Using the defouler trick does not fix the problem.
It only removes the O2 sensor out of the cat, so it won't throw a code

 

[finch13]

You can make you own defouler out of spark plug defoulers.

DIY here:

http://www.civicforums.com/forums/79-forced-induction-swaps/240602-diy-mechanical-o2-simulator.html

 

[finch13]

Be aware though
Using the defouler trick does not fix the problem.
It only removes the O2 sensor out of the cat, so it won't throw a code

My cat is is full working order and I get the P0420 code still. It's actually been throwing that code for 8 years now and never caused a single problem.

 

[blacknight]

My cat is is full working order and I get the P0420 code still. It's actually been throwing that code for 8 years now and never caused a single problem.

Do you replace both 2 sensors?

 

[finch13]

Didn't replace any and I don't have ULEV either.

The primary O2 sensor (wideband for ULEVs) measures the A/F ratio in relation to 14.7:1 and adjusts if necessary. P0420 doesn't have anything to do with it.

The secondary O2 sensor's job is only to monitor catalytic converter function. It could be the sensor or the cat itself.

 

[blacknight]

Then it deffinitely has to be the cat or the O2 Sensor

I had the same problem when I replaced my header.
Click this thread to see what happened

 

[TACORICAN]

Do you all think the car will pass smog with the old Cat that I just recently removed? Half the mesh inside removed from it?

 

[ryan s]

you hollowed it out? enjoy your cancer

would it pass in CA? knowing how strict they are, id say "no"

the p0420 code will stay in the ECU, and if the emissions place hooks your car up to a scanner, it will show it "lurking" in the background as reset but active (the SOLUS scanner calls it something, but i cant remember the name). so if you try to reset the CEL and run the car straight over to the ref station, the code light in the dash won't be on, but the code will be in the ECU as "pending" or something like that. scanners are powerful man...they can show up to 10 past ECU events like CELs.

so yeah...p0420 = bad cat

you might have also gotten an "O2 sensor bank 1" code which is normal. i replaced the cat and left the O2 sensor alone...CELs gone.