How serious is a p0420 code?

The famous p0420 code popped up on me a couple of days ago. I took it to the dealer and they said I need new cats and also a new rear o2 sensor. Total price to fix would be just under $2600!!!! They cleared my code for me and it hasn't came back since. How bad would it be to leave the cats, get a new rear sensor and a new air/fuel sensor? If the code comes back can I just get the urd o2 simulator and be ok? By the way I live in IL and we have no emissions testing.

 

www.google.com

http://repairpal.com/OBD-II-Code-P0420-Toyota

 

The code isn't really that serious. All it means is that your catalytic converter isn't doing its job at reducing the amount of pollution your truck produces.

But if you have to get new tags/plates and have to pass emissions testing to do so you may need to get it fixed.

My truck popped a p0430 (bank 2) code last week. And according to the scan tool data I read both of my cats are bad. So I'm just gonna wait until emissions time to worry. I cleared the code on last Monday and still hasn't come back.

 

I replaced both sensors and the code hasn't come back yet.

 

This might sound funny but had a buddy with same code and he tried using lacquer thinner in the tank, add 20% off thinner and fill up tank and just drive normally. The thinner will flush out the imperfection in the cats. Please try at own risk!!! You can YouTube it and find more intro into it.

 

I would try this before adding that to your tank(I wouldn't put that ).
http://m.youtube.com/watch?v=5icTmYItwiE&desktop_uri=/watch?v=5icTmYItwiE

 

Can't load video on my iPad. But I know it sounds funny about using lacquer and it does work!! Doesn't hurt anything. It's worth $5 investment rather than 2600.

 

Exhaust is a Great place to start! MUCH CHEAPER TOO lol.

I did a bit of reading on this a while ago as I had the code pop up on ours. Unconfirmed as actual issue cause, but saw a few people post about quality of fuel issues potentially causing the code to pop up especially if you short shift (shift 2000 or so rpm) trying to get into 5th as soon a possible and stay there. Especially at lower speeds.

Issue with the fuel was a thought towards "poorer quality" fuels or "high mix" fuels not working well in the system and could potentially pop the 420 code. When reading these accounts I found it particularly interesting as we typically fill up at the same Phillips 66 and had no issues. We were across town and ended up filling up at a Sam's as we were out of fuel. Half way through the tank the code popped up when we were driving in just the same conditions (short shift etc.).

Cleared the code, put some Fuel System Restore in. Been driving for months okay and use the truck quite a bit.

 

Scott I live about 2 hours north of you in Frankfort, Il and we've been doing emmisions tests for 20 years I bet...You are lucky!!

 

I'd replace both front and rear sensors with Densos ($150, not at dealer, Rockauto, you install) before I even thought about buying new cats. Clean the MAF too.

420 is a bad reading on the rear sensor, which monitors the cat performance. That can be due to the rear sensor being bad, the front sensor not doing it's job well enough but managing not to throw a code, a dirty MAF screwing up the ratios, or the cats being bad. As already mentioned, an exhaust leak can also cause it. Cats, being very expensive, are only worth suspecting if you are selling the things or you've eliminated all other causes.

I'd save the bubba approach to "cleaning" your cats until after you have tried everything else short of cat replacement, too...

 

http://www.google.com/url?sa=t&sour...Rma3ghfhUfyXsu2Lg&sig2=RDdf7w4zq9UCD0kZp-3Bjg

Let's see if that works

 

I guess I need to go ahead and do my P0420 write up that I have been working on. It is a bit long and extensive. As mentioned at least once, a P0420 does not necessarily mean the catalytic conv is bad. What it means is that the post-cat O2 sensor is not reading the correct values for what it SHOULD be reading. This code can be a result of an exhaust leak in the area of the cat, poor fuel quality, computer issues (though rare), or a bad sensor. While the idea behind cleaning out your own cat is reasonable, I would NEVER EVER EVER recommend putting lacquer thinner into a customer's car. The car is not designed to run off of it, and while I won't say it WILL cause problems, but there is a risk in burning something other than unleaded gasoline, and I am not willing to take that risk, or recommend it to a customer. I think my P0420 thread is coming long overdue.

 

I was unaware that they did emissions testing anywhere in Illinois. By the way thanks to everyone for their responses. I think I am going to replace both sensors and go from there. Just trying to figure it out as we leave for Gatlinburg, TN on Saturday.