Showing code P0420 for the last 4 months.

You should go to a independent exhaust shop if the catalytic converter needs replacement. After market cats are much cheaper than the OEM. Plus their labor rates would be lower than the dealer. The P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

Hey, Thank you so much for this information. I am having the same issues with a Honda Accord 2012. About 2 or 3 months ago I took the car to the AutoZone to read the codes so they can see what is happening with the car, they said that they were not sure if it was the catalyst converter or the O2 sensors. After that, I immediately took it to the Honda dealership and they told me catalytic converter needs replacement. Engine light disappears/appears frequently. So I replaced the catalytic converter, & the engine light still goes on and off. The car has issues while trying to start it, in a general way it does not feel right. This week, I decided to take it again to AutoZone & the Honda dealership, Both said the catalytic converters are not right even though I just replaced it. Error Codes Read P0420 CATALYST SYSTEM EFFICIENCY BELLOW THRESHOLD B1 P0430 CATALYST SYSTEM EFFICIENCY BELLOW THRESHOLD B2 P0420 CATALYST SYSTEM EFFICIENCY BELLOW THRESHOLD B1 Please help on how to go about it.

We have a 2012 Accord that had trouble starting and just yesterday the check engine light came on. The code is P0420. We're deciding what to do next. Did you resolve your P0420 code?

I mean I was thinking it’s the oxygen sensor/AF bank 1 sensor 1. I think after replacing that the code should go away. Because if it’s the CAT then it will be a pricy 500 replacement