P0420 Nissan

My check engine light is on, the code is P0420, and my cat is failing and needs to be replaced. Here is my question: Since I don’t have to have my car smogged until next year, is it safe to wait until then to replace it? Can driving around with a sick cat be bad for my 2001 Nissan Sentra?

I wouldn’t wait, and here’s why: All new cars have a federally mandated 8-year, 80K mile warranty on emissions equipment which includes the catalytic convertor. If the car is under 80K miles you can get it replaced free of charge.

I know. My car has 87,000!!! Makes me sick! Do you think they may let it slide just for 7,000 measly miles?

If it’s determined that certain scheduled routine maintenance has not been performed, it may not matter how many miles are on the car; but, if you have had all the routine maintenance performed, as it became due, Nissan of America may extend a “goodwill exception” to you.
You can ask Nissan.
There is, usually, something that causes a catalytic converter to go bad. The DTC code for yours says that it’s underperforming. You need to ascertain what may have caused the cat to sicken. Some of the causes are: misfire caused by fouled, or worn out, spark plugs; an overly rich fuel mixture (dirty air filter, etc); engine burning oil, or antifreeze, or silicone (from sealants); low flow from the egr valve (caused by carbon buildup).

Change those filters, tune that engine. Then, the cat may get better.

I bought the car new in 2001 and have had regular routine maintenance, but not necessarily by the Nissan dealer and I have all the paperwork from day one. I have never had a tune up since I have those titanium (??) spark plugs. I have my air filter changed when needed when I do the oil change every 3,000 or so miles. I have had a new head gasket replaced last year. So, I will print out your advice and give it to my mechanic and have him perform these and see if the cat gets better. Thanks

Does this 8yr 80,000 apply to 02 sensors?