Got a check engine light on the car i bought a few days ago.
getting code
P0420
Catalyst System Efficiency Below Threshold (Bank 1)

the person that i bought it from told me that something was up with the cat. not too experienced with catalyst system.
can some 1 enlighten me what does the code mean?

99 civic ex
STOCK other than 2.5' piping

 

 

when i hit the power band at about 4,500 rpm, the sounds changes.
leads me to believe that MAYBE the cat was hollowed out.
but i am not sure.
how can i detect a vacuum leak?
my idle is not high so i rejected that first. but now im starting to wonder

 

ttt

 

If you don't have an exhaust leak, then the cat is bad.

 

where would the exhaust leak be?
pre or post cat?

after a few hours of studying and reading up in this, one of the most common solutions is to replace the cat.
any one know where i can get a high flow cat that CAN be shipped out to cali?
and is legal?

 

If you have an exhaust leak, its PRE cat. Butsounds like the cat was gutted. Some signs is if you have black gritty stuff on your bumper or around your exhaust.

I would just buy Magnaflow high flow cat. I believe they are 50 state legal, but check before you buy. I got mine for $100 and free shipping. Very happy with it.

 

ive been looking and i cant find a magnaflow high flow cat that are 50 state legal.

 

Yea. I see, its 49 state(not CA) legal. You may just have to purchase DEC brand. They aren't high flow, but are oem replacement, thus carb legal

 

quick question i have a ls swap and it came without a cat would getting the integra cat allow me to pass nj emissions? Seeing how the one for my stock y7 will not work?

 

Yes. As long as it isn't too long to fit (i'm not sure if it is or not). I can't remember if you need an Integra cat or a 96-00 EX Civic cat.

 

well i plan on installing my ws2 at the same time so length wont matter much can always make it work and thank you i do believe i would need the integra one because my cat is supposed to be located after the header.

 

well if i just get a high flow 49 state cat, will i be able to pass emissions?