CEL Code P0420 HELP
 

Hey everyone. So about 3500 miles ago I had a check engine light appear on my 01 Maxima 20th AE. I had it cleared and now being driven 3500 miles, it came back. I've noticed that when I drive, I burn a lot of fuel. And I mean a lot. I went to Autozone and got the code checked and it gave me P0420. I need help knowing what it is, how to get rid of it, and how to get my gas mpg back up again. The paper I got from Autozone said:

"-Catalyst system efficiency below threshold-bank 1"
"Large vacuum leak"
"Ignition system fault"
"bank 1 catalytic converter"

Please and thank you. Any help will be greatly appreciated

search this forum tab in the right corner, type in code and do some research

Possible cause: clogged precat
OEM Genuine Nissan Cat cost $599.00 parts only, OEM aftermarket Cat (bosal, walker):cost $299.00
The best and the cheapest way is to gut both precat : precat near the radiator
precat near the firewall.

Install 02 nonfouler to the two secondary 02 sensor, for SES light not to turn on.
:02 sensor with white wire
:02 sensor with red wire.

So should I just buy an aftermarket and get that installed?

colt has highlighted the choices. Spend $300 on an aftermarket and have it replaced or gut what you have, make more power and safeguard against that rear one breaking up and going bad on you. The choice is yours to make.

Got it. So how would I go about gutting it lol

^ take it off and remove the insides

Obx v2