Code PO420 is back!

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Code PO420 is back! #939863 04/11/09 08:04 PM

Joined: Oct 2003

Posts: 56

Buffalo, NY

4barrel

Getting the Wheeling Fever

My MIL Lamp is on for PO420 again on my '99 SR5 4Runner (150K), after replacing the entire exhaust system from manifold back. new cats. new muffler, etc. after replacement, the code went away and I ran without the check engine light for about 3 weeks. now the lamp is back on for the same code. what GIVES? The front sensor is older, could that be it? any input/help would be greatly appreciated!

1999 SR5 V6 4WD
Addcos, Bilsteins, Detroit Truetrac, Amsoil, etc...

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