1999 Tahoe Engine Code 430 and 442

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Klassickarguy

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1999 Tahoe 2wd 5.7L 134K. Just installed Flowmaster Muffler (Dual In Single out - to replace Stock Muffler). Sounds great and runs great but recently developed CEL with P0430 and P0442. I am wondering if it may have anything to do with the muffler change. I cant imagine cat is bad at 134K but maybe? Any Ideas?
 

Klassickarguy

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The P0430 code is set when the ECU detects below threshold performance from the catalytic converter.
P0442 is a diagnostic trouble code (DTC) for "Evaporative Emission Control System Leak Detected (Small Leak). What is an anti fouler?
 

xjsciortino

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The P0430 code is set when the ECU detects below threshold performance from the catalytic converter.
P0442 is a diagnostic trouble code (DTC) for "Evaporative Emission Control System Leak Detected (Small Leak). What is an anti fouler?

Anti fouler is a spacer for the O2 sensor to get it out of the stream of the exhaust gas. Tends to help with cats that are failing or missing completely since it reports a difference between the upstream and downstream sensors enough to make the computer happy.

If you didn't mess with the cats, then I bet it is a bad sensor. I believe the upstream and downstream are the same sensors. try swapping them out and see if the code moves with them. Or just get new O2 sensors and do the spacer trick to be safe
 

xjsciortino

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They are different up/down, one heated one not I believe. They are about $60 new, Advanced Auto has a coupon thingy where can get up to 25% off.....

Good to know. My 06 Silverado had the same sensor for each so that’s what I figured was for the 400s as well. My 2500 doesn’t have rear o2 sensors and my 96 2wd only has the one rear and 3 primary sensors
 

Klassickarguy

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Anti fouler is a spacer for the O2 sensor to get it out of the stream of the exhaust gas. Tends to help with cats that are failing or missing completely since it reports a difference between the upstream and downstream sensors enough to make the computer happy.

If you didn't mess with the cats, then I bet it is a bad sensor. I believe the upstream and downstream are the same sensors. try swapping them out and see if the code moves with them. Or just get new O2 sensors and do the spacer trick to be safe

Have a part number or a link for the anti foulers?
 
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