i now have gone tho 4 cats, keeps popping code Catalyst System Efficiency Below Threshold (Bank 1) P0420. idk what the deal is but i am out of warrenty on my cats now lol ssooooooo what to do


oh its a 2007 cobalt 2.2l with SAI

 

anything modded on the car?

also maybe replace the 02 sensor?

 

header and down pipe with a spun metal magnaflow cat. i just had my 5th stock cat go bad friday. i said f u to the 700 dollar stocker and got a zzp header and dp combo with cat. enough of the stock crap parts

 

does anyone maker a header for a SAI ?

 

check with zzperformance.com

 

k&n intake,jet mass air flow sensor and GMPP catback exhaust, b&m shift +

 

agree talk to zzp, maybe they could even make something. just delete sai. f that emissions friendly crap

 

gonna look into header dp and or tune

 

And. Not or

After you buy my trunk of course lol

 

cobalt list is koni front and rear, cf trunk, 2.4 tb and manifold, header dp and tune lol

 

If you keep wiping out your cats, you may be running rich. Raw fuel will wipe out a cat fairly quickly. I would diagnose the problem before you just throw another cat on. You would have to monitor your fuel trims (STFT and LTFT) This will tell you if your running rich or lean. Also, monitor your oxygen sensors. This would be HO2S11 and HO2S12. Your HO2S11 should be a smooth wave signal that bounces from .1V-.9V (rich, lean, rich, lean) Your HO2S12 is the cat monitor. This should be a steady voltage around .7V and look like a straight line on a graph. If it is not and matches the HO2S11, your cat is beat. Ive seen my share of cats go bad, but to have 4 go bad means there something else wrong. I bet you're dumping raw fuel down your exhaust causing the cats to go bad. Just my two cents. Hope that helps.

 

and how do i do that?

 

You need a scan tool. Or take it to the dealer or anybody that can diagnose your concern.

 

erll i got a scan tool but i guess u need a high tech one

 

You need a scan tool that can monitor PID data. Not just one that pulls DTC's.

 

easy fix...get rid of them

 

running lean will also melt down the innerds of your cat. that was my situation. you get that cat operationg over 800 degrees and there isnt much left of the honey comb. i beleive normal operating temps are arounf 600 degrees cat temp. i also fried an upstream o2 sensor this way. =-)

definatley solve ur issue after u put that cat on. those things get expensive lol