Cat replacement help

ok how the heck do I know what cat I need to replace to cure my 0420 code? Don't want to just guess and it not be the correct one.

 

Bank 1 is the bank with cylinder 1, which is the passenger side. The cats only have sensors after the first cat, meaning if the rear cat was bad your truck wouldn't know to throw an error. In short it is the front passenger cat that your truck is saying is the issue. However it is also possible the O2 sensor on that side is bad.

 

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so I should start with the passenger side upstream or down stream? I bought a down stream today.

 

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if I do end up replacing the cat is there enough room for a weld in?

 

This is the front cat... attached to the "header".


Not much room in there and it welds right to the factory exhaust manifold.

 

That's what I was afraid of.

 

I had URD Long Tube headers installed. So that photo was the actual manifold & cat pulled off my 2015 Tacoma. Unfortunately I've had a rattle in the rear driver side cat ever since (presumably something blew back into it). Exhaust guy told me if the rattle didn't go away (i.e. the object didn't blow out) to come back to see him. I never did. Probably tearing my cat apart by now I'm sure.

Anyhow, the URD O2 Simulator doesn't do shit on my 2015 (Gadget @ URD admits it just doesn't work on every truck). So I've considered getting high flow cats to put up front just to make the CEL go away. Then maybe pull the back ones off (there's no sensor after those so far as I know).

 

Likely not a bad cat.. Do some troubleshooting first, lots of cheaper things that will throw that code.

 

What do you suggest I try ? Only thing I have done so far to make sure I had no exhaust leaks.Tomorrow I’m going to replace the spark plugs .

 

Interchange sensors, the ones after cats, if code remains the same it is your passenger cat that is damage, if it change to 430 then it was your sensor and you need new ones. What year is your truck?

 

My codes seem to come and go . Was on last night. This morning no codes . Have drove about 150 miles and still off . Have not done nothing to it since the last code

 

Get a wifi/Bluetooth obdii reader (ELM327) and an app for your phone (Torque for Android) and watch your o2 readings, fuel trims, and other diagnostic readings.

 

I have a blue driver on order . Should be here Tuesday.
And now my code is back . Soon as I get done helping a buddy move I’m changing the sensor .