P0420, P0430, P0307 Are the CAT's bad???

[jbrown91]

Hello all, I have a 2000 LS V8 and I'm getting these codes. I just replaced VCG's, plugs, and one coil. What else could be bad? The 420 and 430 are cat below threshold... I assume the cats are bad are they not? I check #7 and the coil is good. Any help is much appreciated, thanks!

Also, can you use universal cats on this?
And my car feels like a misfire now and then while driving. At lower speeds you can feel it, I just attributed it to cats... Maybe there is something wrong on 7? Thanks

 

[CobraStar_LS8]

cats below threshold codes are definitely bad cats

that's what happens when you drive it alot while misfiring...the bad A/F ratio damages the cats

 

[FASTLLS]

cats below threshold codes are definitely bad cats

that's what happens when you drive it alot while misfiring...the bad A/F ratio damages the cats

Yessss.. That's what happened to me..

 

[jbrown91]

Okay, thank you. Is the #7 misfire coil or real? Maybe from CAT problem. I JUST bought it a week ago, fairly cheap due to problems. I suspect the old owner drove it with problems. Considering the VCG leaked, had Champion RC12YC!!!! plugs in it(ridiculous!!), and a bad coil. I owned a F250 V10 so familiar with COP. Would this coil be bad as well? Thanks

I have pulled the plug off all the coils and listened to idle, all make a BIG change when pulled off. Though it could just do it now and then I guess. Maybe move it to another cylinder and see if #7 misfire disappears and new one pops up.

Also will universal cats fit?? I know they have to be cut.. But SO much cheaper in the long run!!!

 

[CobraStar_LS8]

if you can cut the old cats off then yeah, universal ones should fit as there are different sizes...as for the coil, are you sure you are lookin' at the correct cylinder? it should be the third one from the front of the car on the drivers side

 

[jbrown91]

I'm pretty sure that's the one I checked. Once I get the cat's done and new rear O2 then good to go I think. I think the cats are a little clogged as well.

 

[CobraStar_LS8]

I think the cats are a little clogged as well.

clogged cats can blow your rings

 

[pbslmo]

I just experienced this check engine light code P0420. I went to Auto Zone and they pulled the code and gave me the print out for it. I then went across the street to Midas who gave me a price of about $2000.00 for new cats ad sensors.

I thought that since I hadn't changed my oil recently it must be causing the sensors to go off, because one of the possible problems was "misfire", and another dealt with "worn rings". I read some of the posts on here about the code and cats so I pulled the pos and neg cables from the battery and reconnected them. What do you know the light went off! It has been a week now, and the light hasn't came back on. Lucky me.

 

[joegr]

I just experienced this check engine light code P0420. I went to Auto Zone and they pulled the code and gave me the print out for it. I then went across the street to Midas who gave me a price of about $2000.00 for new cats ad sensors.

I thought that since I hadn't changed my oil recently it must be causing the sensors to go off, because one of the possible problems was "misfire", and another dealt with "worn rings". I read some of the posts on here about the code and cats so I pulled the pos and neg cables from the battery and reconnected them. What do you know the light went off! It has been a week now, and the light hasn't came back on. Lucky me.

It'll be back eventually.
This has nothing to do with your engine oil.