P0420/p0430 code help

I apologize if this is a duplicate but I haven’t found any threads on these codes for a 3rd gen.




So I’ve been getting a P0420 & P0430 code off & on for about 15k miles now.

Truck is a 2018 3.5L manual 4x4.

245k miles.

87 octane ran 99% of the time.

Spark plugs changed at 150k.

First occurrence was at 229k. Cleared the code & it didn’t come back on until 239k. Cleared it again and didn’t come back on until 242k. Since then it’s been off/on every 500-1k miles.

I’m assuming the cat is probably just failing but I don’t want to throw $100 bills at it.

Can anyone help me interpret the data from my scan tool?

I’ve attached some photos from my scan tool. It’s just a cheap $200 Amazon special so idk how accurate the data is.

I noticed after I clear my CEL ONE p0420 & p0430 code remain in the system if I read it again. I’ll drive some and when the light kicks back on that’s when two more p0420 codes appear bringing the total up to 4. (3) p0420 & (1) p0430.

Is “bank 1” drivers side? I don’t know the firing order.

If there is any other data I can retrieve from my scan tool I would be glad to retrieve & post .

Thank you all.

 

Sometimes it’s the upstream o2 sensor, bank 1 is passenger side

 

I *think* you might be looking at generic Data, instead of manufacturer specific stuff. Are the second pics freeze frame data? How do the fuel trims look?

I'm assuming it's not the cats (both failing at the same time?) But I'm by no means no expert at all.

 

Have you checked to make sure the cats are still there

 

Here's some beta on some trims you can verify

 

Below is the summary from the FSM as to what can cause these codes. Trouble area is the same for both banks so this is just for one bank. Attached is the actual procedure from the manual for troubleshooting as well as a description of what is being monitored that triggers the codes.

In there you'll also see that extremely rich or lean conditions can cause these codes, which would be something upstream that would affect both banks. It would seem odd for cats or sensors on both banks to go bad at once. Freeze frame data would certainly be helpful.

 

Sounds like similar codes when my tundra o2 sensors started failing...one actually rotted loose off the cat.

 

Here are the freeze frames.

thank you for the guide homiec. I am going to print that off & read through it.

 

Dealer once told me when i owned a tundra that the 02 sensors should be replaced every 100k even if they show no engine code check light for better fuel efficiency. They degrade over time.

 

Any ideas? I'm a techstream noob. Not sure what the different color boxes mean?