PO420 - Replacing O2 Sensors?

[jeffhoward001]

2012 3.6L w/ 180K.

 

Hi All -

 

I've done a lot of reading on the PO420 DTC. People say that replacing the O2 sensors is a cheaper place to start versus going straight to a Cat replacement, but has that actually fixed the PO420 code for anyone? Can't find anyone on here saying that it did.

 

Reason I'm reluctant to do it is that the O2's are covered under my extended warranty, but a PO420 isn't actually an O2 sensor fault (there's a different code specifically for a sensor failure). It's the O2 sensors doing their job and saying the thing between them isn't working.

 

So long/short, the warranty isn't going to cover O2 replacements for a Cat code. So I'd rather not replace them out of warranty unless 8 out of 10 people say that it's likely to fix the issue 😂

[5rebel9]

Howdy! I AM one person that did O2 sensors for cat efficiency code and IT WORKED for me. 

These sensors do have a suggested replacement time at 100k miles  Did this on our '11 shortly after buying it with 190k miles on it. On our '14 with 188k miles, and a motor that has 130k miles, I get that code about every 3 months and put SEAFOAM into the fuel tank, clear the code and drive it. BUT am getting ready to replace both bank upstream sensors as they are the ones that actually do the work with fuel controls. The downstream ones just give a reference signal.

  Personally I would suggest replacing the sensors....yup you'll have to spend some money, but cheaper by far than jumping for converters and still having "old" sensors.

Good Luck in how you decide to pursue things.

[2late4u]

9 hours ago, jeffhoward001 said:

2012 3.6L w/ 180K.

 

Hi All -

 

I've done a lot of reading on the PO420 DTC. People say that replacing the O2 sensors is a cheaper place to start versus going straight to a Cat replacement, but has that actually fixed the PO420 code for anyone? Can't find anyone on here saying that it did.

 

Reason I'm reluctant to do it is that the O2's are covered under my extended warranty, but a PO420 isn't actually an O2 sensor fault (there's a different code specifically for a sensor failure). It's the O2 sensors doing their job and saying the thing between them isn't working.

 

So long/short, the warranty isn't going to cover O2 replacements for a Cat code. So I'd rather not replace them out of warranty unless 8 out of 10 people say that it's likely to fix the issue 😂

So if you have the ext warranty and it will cover the 02 sensors,, wont it cover the cat as well?

[John/Horace]

And if you change O2 sensors. Use NTK part of NGK corp, I put them in almost 100k miles ago without issues.

I was doing plugs and had intake removed and the O2 were in the change zone. The upstream one’s like 5 rebel  said are the fuel trim, so affect fuel economy. 
 

I assume you have checked cat recall. Some people got them changed in emissions warranty no charge, but I think 2.4 engine.

 

Exhaust leaks can cause a 420 code as well. Flex section or before cats mainly.  Is exhaust loud?