Check Engine Light

[Blayne]

My check engine light is on and I'm getting a code #0420 = Catalyst System Effciency Below Threshold ( Bank 1 )
It's a 1997 2.3 L, I've run injector cleaner through it twice, replaced both Oxygen Sensors and changed the plugs and the light came back on with the same code, what schould I lokk at next ?
Thanks For Any Help !

 

[kimcrwbr1]

Is it the original exhaust system could be muffeler or cat problems

 

[modelageek]

I read somewhere that occasionally the egr vlave/system could be the issue but I bet it is the cat itself. after driving it for a while you should look at the cat and see if it is super hot see if it is glowing at all.......the best way is to get a scanner and you can read the system and see if it is running correctly. if it is, the cat is bad....if the system is running rich and the cat cant keep up then it is something else........my guess is the cat is bad.......

 

[SMTGREG]

P0420 cat efficiency is just that. You are not getting codes for the O2 or Monitor sensor. It's time for a new cat.

 

[The Toolman]

My ck eng lite has been on for 6 or 7 years now. Gas mileage hasn't really changed from when the lite was off when we bought it. Still runs an sounds great.

Don't hafta worry about any smog ck down here in the Mo. Ozarks.....

 

[disciplerocks]

Bank 1 is a reading from the front O2 sensor, before the cat so I dont know how it could be the cat, but at this point I dont know what else it could be.

 

[disciplerocks]

Googled it:

The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.