What that particular code (P0420) is saying, is the Cat isn't converting the engine exhaust properly and the rear O2 sensor (Bank-1 Sensor-3 (after the Cat)) is showing the same reading as (Bank-1 sensor-2 (before the Cat)) or close to it. Either way, the Cat is out of the required threshold for converting the engine exhaust. Hope this helps.
If the problem started right after the Cat change then yes, have them re do it. The OEM Cats are a "3-way" Design. Some of the after market cats are only a 1-way design and aren't up to the required Specs that the OEM ones are. Hope this clears things up and sorry for the delay.
It's not an upstream or downstream O2 problem. It's Cat problem not converting the exhaust gases properly, that's what that code is saying to you. get them to "re-do" the Cat (if this problem started right after they changed the Cat), it isn't up to Spec. as mentioned earlier. Hope this helps.
Sorry, forgot to mention that. The p0420 code was my whole reason for having the cat changed. I changed the other two sensors myself and will clear the codes tomorrow and see where it stands. So now I have a new cat and all three new O2 sensors.
Cleared the codes this morning and they are back. I called the shop and inquired about the cat, 1 stage or 3 stage. They confirmed 3 stage but are going to install a new one at no charge.
Should this not fix it, I will be finding a high cliff for Astro diving!
I would test that O2 sensors were within specs before I would have them tear off a new cat again. It's not legal to sell or install cats that don't meet performance specs, whether they are one, two or three way.
Had the shop replace the cat (at their cost!). Got my van back and have about a hundred miles since picking it up. No codes...guess I can get my registration now!
fyi: code used to come on before I would get 30 miles down the road...
Maybe a bad one or they put it on backward (don't know if this matters)...don't know.
:layrubber: :layrubber:
Brad
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