another question, had P0420 is the code for a bad cat........had it replaced, cleared error, drove it and lite came on again, same code. so after reading what may fault the cat, looking into O2 sensor upstream. plugs fairly new, still 15 mpg in the city, secondary plugs not changed at last spark plug change, they always look new, so changing every other time (they are a pain) anyone experience the P code for bad cat in bank 1. runs great no other symptom's.

 

Rear O2 sensor is what monitors the cat.

 

Thanks Heyyou will monitor and change, error didn't come back on today. Short drive with this Hemi, need to get it on the big road and put my foot in it......then 02's are couple yrs. old.

 

We have seen a real problem with aftermarket cats on Hemis. If it's one of those skinny pieces of crap from a muffler shop, you might never get rid of that code. Been down this road several times already. Just be aware.

 

its not the pill looking thing(cat) that was taken out. This one I am guessing still aftermarket , has heat shield and is twice as big as the old one. replace BK 1 rear O2 as well.
thanks for heads up........