![My Cats are Empty [P0420 Check Engine Light]](https://live.staticflickr.com/65535/54550567999_6bda364eed_c.jpg "My Cats are Empty [P0420 Check Engine Light]")
TL;DR - I've been getting P0420 check engine lights for a while now. I'm not planning to do anything about it for the time being.
This is annoying, but I can live with it to not put a new catalytic converter in.
I started getting an intermittent P0420 check engine light several years ago. It occurs - almost entirely - when I'm putzing around in the middle of nowhere in 4-Lo. The first time I got it, I was a bit worried, but after learning that it doesn't affect drivability, engine operation, or fuel economy - at least, on a 1st gen Tacoma - I've pretty much put it out of my mind, save for what has become a once-a-trip reset using my ODBII scanner (there is now a much cheaper device that is basically the same).
A hot commodity... or so it appears.
With my Tacoma being a California model, a new CARB-compliant catalytic converter - Toyota OEM Catalytic Converter (17403-07041) - runs upward of $1000 these days. Even an aftermarket Magnaflow is only a couple hundred dollars cheaper.
With thefts of the devices taking place more and more frequently, I think I'll stick with what I've got. If mine gets stolen, at least I'll have the last laugh when they find it empty.
In this Series
Since the P0420 started intermittently I would lean towards the rear O2 sensor failing. But depending on its failed state it could damage the cat over time. Then as you say it runs fine, so don't mess with it.
Interesting and definitely possible. I should probably freeze frame the rear O2 on my obdii just to see what it's doing. I mean, I wouldn't be opposed to throwing in a new sensor; certainly a lot cheaper than a new cat, lol!
I get those from time to time on my wife's Honda Pilot. I've been successful in holding it at bay with a can of CRC's "Guaranteed to Pass" swill every time it comes on. I can go through a lot of cans of that stuff before I replace the cat.
Exactly 👍