P0420 code with a side of gas smell

That's some solid real life input man

 

check it out, if it leaking after you refill the gas tank dead giveaway

 

Always appreciate any possibilities to look into, I'll check on this and report back

 

It says in this article that if the O2 sensors are dirty or failing that it could lead to heavy gas smell in the exhaust and a failing cat smells like rotten eggs.

It definitely doesn't have any egg smell... can O2 sensors be cleaned safely?

 

I wouldn't clean them, depending on the mileage some say to replace them at 90k-100k miles with either DENSO or NGK brands,also if the sensors are bad on your OBI Scanner should have a p0420 bank 1 or bank 2 sensor listed bank1 is the forward sensor bank2 is the rear sensor that needs replacement https://www.youtube.com/watch?v=es9ItFprLZk

 

Filled up till the nozzle shut it self off.. drove 10miles and I've got no leaking fuel near where was mentioned... even crawled under it and fondled the top of the tank as best I could, I'm good there.


You lost me on that last video.. didn't really give me an real useful info given what I've done/changed/checked on the truck already.



I agree with bishop cruiserguy and glamisman that my cat needs replaced given the numbers from my scanner but my question is can a bad cat smell like anything other than rotten eggs? Cause I put my face right in the exhaust and it's all gas smell no eggyness

 

just got to make sure its something else other than the Cats because they are very expensive and usually only OEM Toyota ones will work out, other aftermarket cats cause issues with Toyotas. when you checked the engine code with the scanner did it give you a Sensor Bank 1 or a Sensor Bank 2 with the P0420 this work indicate a bad 02 sensor Bank 1(front) or a bad AFR sensor Bank 2(rear) which are reasonable cost and easy to replace, before the Cats purchase

 

Appreciate the good looking out, it never hurts to make sure some does the basics first.. you know what they say, keep it simple stupid!


There was no other code with the P0420 indicating neither (front) 1 nor (rear) 2. There was only the P0420 Catalyst System Efficiency Below Threshold (Bank 1). I only have 1 bank cause it's the 3rz. If there was something specific to an O2 sensor I should see a P0135 or a P0141 right?

 

https://parts.olathetoyota.com/p0420-code-toyota based on this article the safe bet would be the 02 sensor first and the CATs second there must be a way to test the 02 sensor with the scanner 02 voltage readings to pin point the issue would be the 02 sensor (hopefully) would be a low cost DIY fix. if you read paragraph 2 the P0420 refers to the 02 sensor specifically, if it were CATS you have a P042X code, looks like a bad 02 sensor