PO420, 430 Code issue-Catalist efficiency below threshold

Hey all,

First post here..
Bought a 2006 4 Runner 6 cyl that had a couple of misfire codes repaired with coilpacks and plugs. THEN, the PO 420 and 430 codes showed up. I have Techstream software and am comparing 2006 Lexus O2 system numbers with the 4 Runner. The O2 info for bank 1 sensors and bank 2 sensors seem very close-within limits for both cars, despite the fact that the Lexus 3.3 L has no codes. (Lexus data, top, 4 Runner, bottom). Could the slight difference in lambda and downstream sensors trigger the codes, or do they reflect bad converters? In other words, could it be that the sensors are "telling the truth" and pointing to a bad pair of Catalytic converters, or would you suggest replacing the downstream sensors? The CATS sure are pricey and I hope sensors could be causing the issue. Any thoughts, 4 Runner GURUS? RD

 

Yes.

 

How many miles? O2 sensors get slow with age, which could trigger the codes.

Burning any oil? Dirty PCV? Take a look at intake deposits.

Odd to see both banks afflicted at the same time, but it was driven with active misfires on both banks, could have damaged both cats.

 

Welcome

 

-I think it was driven with 2 bad coil packs, one on each bank

 

If this is the case, it probably needs new cats and new O2sensors (if original with 197k)

If you don’t have emissions testing in your state, there are ways to prevent the downstream sensors from triggering the code. Of course, that may or may not be illegal so you can explore that option as you see fit. Also, if the cats were damaged from the misfiring, it may have resulted in clogged cats, which would have to be, ahem, rectified