Newly purchased 04 4runner Code P0420 & P0430

[scrowley]

Well I just bought a 04 4runner 6cyl. from a used dealer and drove it for a couple days and now have codes P0420 and P0430.....Both front cats!! Truck runs perfect. Can't believe both fron cats (exhasut mani combo) would be bad at the same time. Dealer want $1600 ea. plus labor...Not happening. I am thinking of throwing in some O2 sims for awhile. Any others thoughts?or suggestions?

 

[liljlandon]

How many miles? I replaced my front cat at 160k. It could be a down stream 02 sensor as well.

 

[scrowley]

has 115k miles. When I hooked up my scanner I monitered the o2s at idle/hits on gas and it seemed that bank 2 rear was reading slow and a bit different than bank 1. But why would the code be po420 and po430? Both cats. These trucks are highly overboard for the emissions. It has 4 cats total and the rear two are not even monitered

 

[TheDurk]

My guess is the seller reset the codes before the sale to turn the MIL off. As it takes a while to work through the emissions drive cycles to complete the tests it took a few days but the codes came back, as I am sure he knew they would. Always take a code reader to a used vehicle before a purchase as this happens all the time.

 

[scrowley]

The seller put in a rear cat as is must be cali spec because it has four total. The rear cats are not even monitored. Anyways he said his scanner said rear bank 2 rear cat. Who knows in this case what to believe. I ended up getting a $500 refund and walked with that. I am going to try some spacers on the rear O2's. and see if it will get the light off. Any other suggestions?

 

[SC T100]

has 115k miles. When I hooked up my scanner I monitered the o2s at idle/hits on gas and it seemed that bank 2 rear was reading slow and a bit different than bank 1. But why would the code be po420 and po430? Both cats. These trucks are highly overboard for the emissions. It has 4 cats total and the rear two are not even monitered

Just curious, but why not try to replace both O2 sensors (with Toyota OEMs if possible, as Toyotas are notroius for not liking most aftermarket brands) since they were acting wonky? There are a ton of threads I found just googling the code where once the O2 sensors (both the upstream and downstream) were replaced the CEL went off and the mpg went up. As some of the other threads said, most cats don't just go bad on their own, especially at lower miles. There are quite a few T100s running around with 200-400K on the original coverters. Maybe I am missing something here?

Heck if nothing else it might be worth a shot before shelling out a grand for a new converter. If it were me I would take some of the $500 refund, buy some OEM, Denso, or NGK O2 sensors and swap them in and see what happens. Amazon has them for around $70 apiece last I heard.

 

[SC T100]

Also, it doesn't make sense he would replace the unmonitored rear cat based on a code reader. How would the ECU know it was bad if it's unmonitored?