bad catalytic converter

i have a 2005 toyota tacoma dbl cab v6 4x4 trd off road. it has 250000miles on it . engine light came on with p430 and p420 codes . took to the dealer they analyzed and said need to replace both upper manifold assy. had the work done today got truck back left the dealership drove less than 2 miles light came back on. took back to the dealer hooked back up now says it is a bad rear 02 sensor. they said they will replace at their cost. my question to you is could that have been the problem in the first place.

 

Possible but pretty unlikely especially to cause codes for both banks.

They may have damaged it when they removed it to replace the converters or it was just on it's way out and messing with it finished it off, I've had it happen to me when removing them for other unrelated work.

 

ok thank you , also should they have replaced the upper 02 sensors since they were replacing the two upper catalytic converters.

 

I mean with 250k miles if they are original it would be a good idea to replace all the AFR & O2 sensors.

 

No need to replace the upper o2 if there's nothing wrong w/ them.

 

I am getting into these codes at 240k, also an 05 v6. From what I can tell, this is a typical service life for the catalyst.

Of course it is frustrating that the code returned in this case -- and the dealership owes it to you to correct whatever issue remains if this was a case of blatant misdiagnosis, because that was an expensive repair!

Another potential cause could be a weak fuel supply -- or so I've read, although I can't yet figure out how to connect a pressure gauge to my fuel rail. If this is the case -- again based only on what I've read -- the likely remedy is to replace the pump/filter assembly in the tank. (It may simply be clogging of the filter, but why not replace the pump at this mileage as well?)

But, regardless of whether your catalyst was actually fully worn out... I would like to thank you for properly maintaining your truck. I am sick of the mentality that defeating or neglecting our emission systems is in any way acceptable for road-driven vehicles. It is not.

Hope you enjoy many more years with the truck -- and good luck getting to the bottom of this!