Trouble Code P0420 and Terrible Gas Mileage in 2001 Maxima SE

[bjgpp]

Hi guys,My engine light in my 2001 Maxima SE came on with a code P0420 (Catalyst Efficiency below Threshold Banks 1&2). So I immediately took it to my Nissan dealership. They told me i needed to replace the cat, but I don't think it is my cat because i am not having any performance issues of any kind. The only issue I am having is HORRIBLE gas mileage (about 225-250 miles per tank driving like a grandma). I have heard that changing the o2 sensor has helped this code go away, and with my gas mileage that I am getting it makes sense to change the o2 sensors. My car has 110,000 miles on it and is out of warranty. I also don't have alot of money =)

What do you think I should do? Any Advice?

Thanks,Brendan Grey

[allensteiner]

you can find o2's cheap on ebay. also if you get your car hooked up to a good scanner it'll tell you if you're running rich/lean etc. those are damn expensive to buy so check your local mechanics if they have a snap-on computer/scanner - or any other good brand.