I've been throwing this code for awhile and can't figure it out. I've replaced both o2 sensors and the cat. Anyone else run into this code and figure it out? Also non foulers will not work

 

What year? What cat or test pipe?

 

What brand 02 sensor?

 

I threw that code in my 2002 4Runner right after I had gassed up and the weather went from extremely code to 60+ degrees. Also thought I'd NOT tightened down the gas cap after fueling. The code description was CAT or O2 sensor ,,,,,,, I added a bottle of Lucas fuel injector cleaner .. tighten down the gas cap and filled up next time from a different gas station about a week later. I haven't seen the code since ..... my $0.02

 

2006 and all oem parts

 

Also stock cat no test pipe, I tried to run a test pipe after I got the code. I used the non foulers and it threw a o2 slow response

 

Anyone?

 

Someone has had to of solved this puzzle of a code before.

 

So you have a New Honda cat, and two New Honda o2 sensors and you are getting a P0420?

 

Did you make any changes to the car previous? All the connections are clean and good? What code is thrown when the sensor is disconnected I eonder