I moved this to 'Problems'. Plenty of threads have addressed this. P0420 is bank 1, P0430 is bank 2 (cat capacity below minimum threshold). And per the diagram I've posted, bank 1 is along the firewall, back 2 is out front.

 

Thanks , that's where I meant to post it and hey thanks for your contribution to Sienna chat. Appreciate it

 

Well , my internet research shows this CC to expensive...It appears to a one piece integral with the exhaust manifold $1100 or so...geez

 

Well , my internet research shows this CC to expensive...It appears to a one piece integral with the exhaust manifold $1100 or so...geez

Yes the OEM cats are expensive. Are you sure it`s your cat that is gone. You could try a cheaper aftermarket Cat. Look on ebay or Rockauto for replacements.

Regards, JC.

 

jc..no Im not sure, there isn't a code for a faulty O2 sensor either. I saw Walker brand for under 200 on amazon . Guess I would need a new gasket and seal. Tempting!

 

I had the same problem and I fixed it for $30 with an oxygen sensor spacer. The values the sensor were reporting were apparently out of range, but only just - as I could clear the CEL and it would stay off for a week or two, then come back. I have passed emissions with this, but I doubt it would fly if it were noticed during a more detailed inspection. Don't care though, I have saved big bucks by using this and I'm "code free" for two years.

Before:

After install:

 

My Outback was throwing a O2 code and it was caused by the ecm programing was old there was an update that I did not have, after the update everything is great. I had changed O2's and tried the spacer but cel always came back. The ecm update did the trick.