my check engine light is on and the code is:
P0420 - Catalyst System Efficiency Below Threshold

i have a full exhast system with an aftermarket catalytic in my 2001 Honda Prelude SE. my brother inlaw is a mechanic and said its because of the aftermarket catalytic and that i would have to replace it with the stock one which would cost a lot of money. i took it back to the store that installed my exhast but they said that all the wires were fine and to bring it to the dealership because the check engine light is on. i don't understand why these guys would replace my catalytic with an aftermarket one if it would cause problems. what is REALLY wrong here? how can i fix this? or could it be just a bad O2 sensor?

did some surfing and bumped into http://www.automotiveforums.com/t182586.html i think this is my problem or does anyone have any other solutions?

 

to fix the check light put on an o2 simulator, it will clear the code

 

can you please url me a site where i can get more info on o2 simulators? like how to install them and which one to buy for a 2001 honda prelude se?

i found http://www.o2simulator.com/ good place to order?


Modified by eMonk at 10:45 AM 1/4/2005

 

do a search for the casper's one, its the simplest one they have, plug and play

http://kteller.com that is where i got mines from, its not a casper's but gets the job done

 

i found this Caspers O2 Simulator @ http://www.highrevmotorsports....=1108 is this the one i'm looking for? i have a 2001 honda prelude se.

 

I dont see how a bad cat code equates out to needing an O2 sim for a secondary O2 source. If he got an aftermarket cat, then he should have the secondary plugged in. Cat is probably junk. Go back to that shop and have them cut/reweld the stock cat back in . OR buy a new OBD2 cat for about 300-400 bucks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98TypeSH &raquo;</TD></TR><TR><TD CLASS="quote">I dont see how a bad cat code equates out to needing an O2 sim for a secondary O2 source. If he got an aftermarket cat, then he should have the secondary plugged in. Cat is probably junk. Go back to that shop and have them cut/reweld the stock cat back in . OR buy a new OBD2 cat for about 300-400 bucks.</TD></TR></TABLE>

secondary O2 monitors the efficienty of the cat...so replacing the secondary w/ a O2 sim would make the computer think that the cat is fine...

as far as why...maybe some aftermarkets cat are not up to par w/ honda OEM specs?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by graphic &raquo;</TD></TR><TR><TD CLASS="quote">secondary O2 monitors the efficienty of the cat...so replacing the secondary w/ a O2 sim would make the computer think that the cat is fine...

as far as why...maybe some aftermarkets cat are not up to par w/ honda OEM specs?</TD></TR></TABLE>

you are correct, the only high flow cat is see on the market that is even worth looking at would be the ones from random tech, but the price is

 

i actually had a new aftermarket cat installed. everything is wired and installed properly. i just ordered the o2 stimulator. thanks for the much needed help guys! i will post again in a few weeks once i have it installed and let you guys know how it went.

 

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