my SES light came on last night-about 300 miles after borla cat back install- and i got it read and it came up catalyst inefficiency. The borla was welded on by a shop (b/c i bought it used and it was welded already)- could the heat from welding blow the O2 sensors? I HIGHLY doubt that my cats are bad b/c I haven't touched them and I only have 23k miles on the car. I'm prolly gonna replace the O2 sensors- OR should I just order O2 sims to replace the sensors?

 

Wow-it's $70 for EACH O2 sensors from autozone and it's only 90 for a pair of O2 sims from speedinc. Would I get any problems running O2 sims? I don't see any problems with it but you never know. I don't have to pass emissions here and I'm really not ready to do a LT install but maybe in the summer...

 

On my 00 Z28 my drivers side CAT went bad a month after installing a SLP LM and the car only had 14,000 miles. Had them put a new one under warrenty... even though now I no longer have them .

 

The cat itself went bad? Do you think it was related to the LM?

 

Yep. The dealer said it had to do with no back pressure, but I don't really belive that. I think this happens when water somehow builds up in the CAT when you don't drive the car long enough distances.

 

The only way to know for sure is to check rear O2 sensors for activity but in most cases a cat ineffeciency code is for a bad cat, if you plan on keeping your cats try to have them replaced under warranty, if not try sims or edit and see if the code goes away

 

Yup cats go bad, they loose the ability to store O2 & the PCM detects this.
It may be OK on the tailpipe emissions but the O2's can see the catalyst degradation.
I wonder if the battery was disconnected during all that welding though?

 

battery was not disconnected (what would that have to do w/ anything?). I would still be pretty suprised if the cat went bad after only 23k miles. My car is no longer under factory warranty b/c it was bought in Aug of 00. I think I'm just gonna order sims on Monday and hope this goes away-if not, I'll have to take it to Midas or something. Stupid sensors.

 

yea, i just had that problem, that light came on with that diagnosis, everything was fine till i drove to the beach, my cat grenaded inside, and made a horrible noise, caused another code for knock to go off...get rid of them if u can, if not, get it changed

 

I had this exact problem on that exact vehicle, a 2001 WS.6. Got a P0420 code, catalyst inefficiency on my car that has 24,000 miles. Dealer replaced the cat and O2 sensor under warranty, and I have a lid and cat-back. Take it to the dealer and let them hook you up with a new one.
By the way, the warranty on emissions equipment is 8 yr/80,000 mi. so you're still good.

 

freaking sweet -Q- thanks for the info. I had no idea that it was 8 year warranty that is awesome. Do the dealers know this as well ?

 

All the solid state controllers on you car are not very fond of the electrical spikes produced by an electric arc welder.
Have replaced PCM's & others for this very reason, just a FYI.

 

Oh yeah, they know it too. I just walked in and they took the car no questions asked.

 

passenger side cat has to be replaced according to the dealer.