Allright, i just bought a 98 gsr out of state in order to register it i had to get emissions checked. I failed. The code he gave me was P0420 Catalyst System Efficiency Below Threshold. Now how should i go about fixing this. I have hp racing headers, a jackson racing 2.5 " cat, and comptech catback. The car seems to run fine, just smelling the exhaust it smells a little rich but im not saying it is for sure. The car runs and idles fine, good throttle response, low end power is a little weak, but then again this is my first 4cyl. Topend is real strong, i would never guess anything was wrong with it.

The code that the shop gave me was P0420 Catalyst System Efficiency Below Threshold

The guy before me pulled the check engine light bulb. Now do u think this is a cat problem? Maby its not functioning proberly? Or do u think one of the O2 sensors went bad? How can i find out? And were should i get the sensor and the cat for the best price? Thanks, Ryan

 

Advanced auto for the O2 sensor. It should run you ~40$ for the non-universal one (recommended). Putting it in shouldn't be a problem since you don't have a stock manifold. I don't know about the room in integras, but stock exaust manifolds in CRXs leave no room in the CRX engine bay to change the sensor.

 

So which o2 sensor do i need the pre cat? Or the after cat?

 

Does anybody know?

 

you need to put a new CAT or the OEM CAT back on and have it re-tested. the code they gave you is telling you the CAT is below its threshold.......meaning it not working properly.

 

yes. first of all, put the bulb back in so you can find out what is wrong.. then you can check the code..

if anything.. seafoam the engine through the brake booster line. my friend failed his emissions big time last week, i seafoamed it.. passed with FLYING COLORS.

and I just tested mine yesterday and past with flying colors too.. SeaFoam works!!!!

put half a bottle in your gas tank before you fill up, and through the brake booster line, then if you need to change your O2 Senor(s) you'll pass easily.

 

P0420 Catalyst System Efficiency Below Threshold

thats the code...hope that helps u somehow

 

but that code wouldnt be given, if cat was working, but one of the O2 sensors was shot? Its definatly the Cat? Do oversized cats usually fail emissions?

Does anyone have a stock cat they could sell me, or know where i could get one.

 

po420 is a bad catalytic converter