OK I've done my fair share of search's but still have'nt quite got a straight answer. so maybe someone can help. I have a 2000
3.8 and Im getting code p0420.catalytic inefficency bank 1.
I have a high flow cat, so is it the cat or O2 sensor.

thanks in advance

 

Maybe check this, I only skimmed it but might help you...


http://www.camarov6.com/ubb/ultimate...;f=25;t=005414

 

I'd pull the sensors and see if they've got a lot of buildup on them and go from there. The sensors don't seem to like certain aftermarket cats so maybe o2 sims would be the way to go.

 

This seems to be a prob with the 00+'s.

Stock is a 2 stage cat...after markets are 1. The sensor after the cat "sees" the difference since it expects the results from the 2 stage. Thus the SES.

You can try an o2 sim...but I hope you kept your old cat if there was nothing wrong with it.

 

doh! I did'nt, but as long as nothing is getting hurt I dont mind the ses light.