said by Anonymous_:i bought a 02 grand prix with a hollowed out cat and it was throwing this code, my 97 grand prix also threw it. replacing the cat fixed it.
getting a new issue
catalytic converter code P0420
P0420 Catalyst System Efficiency Below Threshold (bank1)
I think the o2 sensor needs replacement because of the fuel regulator issue ,cause it to get "dirty" due to the rich mixture.
Not worried about passing smog since that is 9 months away
I had it reset to see if it comes back on maybe just a fluke.
Not getting any smoke out of the rear end tail pipe.
Please no tree hugger crap in this thread .