2001 Maxima SE Anniversary Edition 130k miles
Has had long history of intermittent PO420 error codes that I used to be able to reset with my code reader.
The CEL (check engine light) would say off for months at a time.
Now CEL comes back on after only a few miles of having been reset.
I've replaced O2 sensors, coil packs & had fuel injectors cleaned/checked.
MAF has been replaced.
Car runs good and gets good mileage, smog #'s are actually pretty good, except for stupid CEL, which here in California means a "No Pass" on the smog.
So, looks like cats are bad or at least the pre-cats.
I really, really, really, really hate throwing a TON of cash on new cats, especially for a car with 130k miles on it.
Does anybody have a complete Cali spec cat set up off a low mile car?
It only makes sense to replace all three, but I just can't justify blowing $1800+ on a $5000 car.
Advice please!!

'Crabs

 

Well, if you don't want to spend a bunch of money replacing the manifold cats, look into getting some O2 sensor emulators. Don't ask me how to install or where to purchase, I have no experience with them. But the concept sounds promising. OR you can relocate the sensor from the bad cat to behind the main cat further down the exhaust line.

Either way, it will take some work, and you will have to buy parts. There is no easy or quick fix for this assuming it truely is a failing cat converter.