Should I replace upstream o2 sensor(s) to see if p0430 and p0420 are really the cats? (3 Viewers)

[Beej]

Hey folks,

I've got a 2008 with 220Kish on the clock. I've recently come into the truck. It was my sister's though, so I've actually been maintaining it for years.

It's got p0420 and p0430. I replaced the Drivers side DOWNstream o2 sensor and I noticed the o2 sensor was not a Denso (or OEM) part. Anyway, I was feeling confident. I cleared the codes. Today, both codes came back. I was hoping that only one code would come back and this would mean I just needed o2 sensors.

Here's my question. Is it worth replacing the UPstream sensors to really make the experiment fool proof? Those upstream sensors might be some kind of cheapo sensor that's throwing the whole thing out of whack. Its a long shot but its cheaper than new cats.

Thanks in advance for any thoughts, opinions, or ridicule, as appropriate.

Pics are of the new sensor and also of new and old together.

-- Beej

 

[lilevo]

You can throw all 4 new sensors at it if that's your diagnosis method. If it doesn't fix it then you need to replace the cats.

Techstream and other diag software allow you to increase and decrease the fueling to check the responsiveness of all 4 O2 sensors. If they all respond in unison then there is nothing wrong with them.

At this point you would be better off trying this Amazon.com: Liqui Moly Catalytic System Clean 300 ml 7110. Cleans The Injection System and The Combustion Chamber. : Automotive - https://amzn.to/4nErWYk

It could clear off some of the carbon on top of the cat that would in turn increase the efficiency of the cat and maybe be enough to not light the codes.

 

[Beej]

I gotta get TechStream. I know there are threads on it. Even if I already had it though, I wouldn't have know that. Thanks.

I'm in AZ. Truck is registered in another state. Here in AZ, you can't have any codes or you'll fail emissions and you can't register the vehicle. So, maybe the chemical solution is a good one.

 

[lilevo]

I have a whole video on the testing process coming soon, it's in my youtube queue. I think that video will be out on 10/5.

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I'd recommend the cleaner though first based on my testing. I've had P0420 and 430 on a few trucks and the O2 sensors definitely aren't the problem. People really need to use premium gas and beat on their trucks once in awhile to keep everything cleaned out in there.

 

[Timujin]