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2003 Tundra 4x4 4.7

Got the PO420 code and because of the great advice on this site, ordered all four sensors from RockAuto($183) and replaced them all. Was good for about a week and the CEL hit. This time PO136. Pulled the passenger side downsteam, scraped the old gasket crud, reinstalled and cleared the code.

It keeps hitting, what should I try next?
 

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Once you've given the O2 sensors another going over and cleaning them up again; take a look at the fuel grade used. Maybe where you fuel up has old/contaminated fuel.
Also if a tanker is topping of station tanks it will disturb sediment and is possible to fuel up with dirty fuel.
Last item for consideration may be to clean out MAF sensor as well. It may help tell computer about the fueling system for ignition and maybe a clean(er?) burn.

Keep us updated.....
 

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2003 Tundra 4x4 4.7

Got the PO420 code and because of the great advice on this site, ordered all four sensors from RockAuto($183) and replaced them all. Was good for about a week and the CEL hit. This time PO136. Pulled the passenger side downstream, scraped the old gasket crud, reinstalled and cleared the code.

It keeps hitting, what should I try next?
Try disconnecting the battery terminals. Disconnecting the battery terminals for 15 minutes to overnight will reset the ECU.
Resetting the ECU will force the control module to re-learn the fuel trim with new O2 sensors installed.
 

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Discussion Starter #4
...Last item for consideration may be to clean out MAF sensor as well. It may help tell computer about the fueling system for ignition and maybe a clean(er?) burn.

Keep us updated.....
Try disconnecting the battery terminals. Disconnecting the battery terminals for 15 minutes to overnight will reset the ECU.
Resetting the ECU will force the control module to re-learn the fuel trim with new O2 sensors installed.
Did both of these.... I don't know if it was one, the other or both but I seem to be good! Thank you Gentlemen.:tu:
 
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