# 2014 Chevy Cruze LT P0420 (no visual issues, annoying code)



## Abe2677 (9 mo ago)

Hey all, I've got this P0420 code I've had for about a week now. It just started to get warm here and the code tripped. 

There is no issues physically from what I can tell. No bad smell, smoke, etc. Nor is there a difference in my MPG. Since that time it's gone down SLIGHTLY but I've been using A/C and drive more city now. I've checked the majority of old threads here but most are from the catalytic recall period. My car has already gotten that replaced by GM.

I'm inclined to think it's my O2 sensors. My code reader was analyzing voltage and the O2 sensor 1 was going from 0 to its voltage repeatedly. O2 sensor 2 was holding steady. 
Just want to get this code off my car and hopefully not be a catalytic converter problem. From what I can tell, it's not that. 

Thanks in advance, gotta pass emissions and this will fail me.


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## Bvogt (Dec 19, 2021)

You could swap sensors and see if the code reappears on sensor 2. Then you will know #1 is bad or dirty


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## Blasirl (Mar 31, 2015)

Bvogt said:


> You could swap sensors and see if the code reappears on sensor 2. Then you will know #1 is bad or dirty


The sensors are different on the 1.4


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## Bvogt (Dec 19, 2021)

Oh, figures. I’ll go back to diesel country now lol


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## landrystephane92 (Jan 3, 2012)

usually 420 is the cat going bad or exhaust leak between both O2 sensors.


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## Hunterderjunge (Oct 11, 2021)

Abe2677 said:


> Hey all, I've got this P0420 code I've had for about a week now. It just started to get warm here and the code tripped.
> 
> There is no issues physically from what I can tell. No bad smell, smoke, etc. Nor is there a difference in my MPG. Since that time it's gone down SLIGHTLY but I've been using A/C and drive more city now. I've checked the majority of old threads here but most are from the catalytic recall period. My car has already gotten that replaced by GM.
> 
> ...


It's gonna be the cat if there are no other codes. You've got 2 options in my eyes. 

1. New OEM catalytic converter. 

2. O2 sensor bung extender. This goes on your downstream o2 sensor and sort of 'tricks' it. It's not foolproof but so far mine has kept my p0420 code away for 4 months now. 









O2 Bung Extender


This is an O2 bung extender that can help with fitment in the downpipe tunnel. It is made from Stainless steel, has straight and a 90 degree bend so you have two options for the best fitment. The 90 degree extender angle is adjustable so it can fit in any position. Not for use on primary O2 sensor.




zzperformance.com


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## Blasirl (Mar 31, 2015)

Abe2677 said:


> Hey all, I've got this P0420 code I've had for about a week now. It just started to get warm here and the code tripped.
> 
> There is no issues physically from what I can tell. No bad smell, smoke, etc. Nor is there a difference in my MPG. Since that time it's gone down SLIGHTLY but I've been using A/C and drive more city now. I've checked the majority of old threads here but most are from the catalytic recall period. My car has already gotten that replaced by GM.
> 
> ...


A code *P0420* may mean that one or more of the following has happened:

Leaded fuel was used where unleaded was called for (unlikely)
A damaged or failed oxygen / O2 sensor
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
Failed or underperforming catalytic converter (likely)
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure
Cylinder misfire
Oil contamination
Read more at: P0420 Catalyst System Efficiency Below Threshold

Brian V. said:
A catalytic converter has a lifespan of 10 years at which time they tend to
Clog and the precious metals react with an adverse chemistry ..
A good 1 will appear to be charcoal white . a bad 1 will appear dark black ..

Chemical make up of the metals exposed to the extreme heat generated over long periods of time contributes to the degeneration of these metals .. and if there is an excessive amount of rich burning cycles produced for the cat to eliminate from the exhaust streams this may have a possible affect on the longevity of said catylitic converter ..






The Misleading Nature of the PO42O or PO430 Code







www.discountconverter.com


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## rwagoner (Aug 15, 2020)

I can't prove anything, but I think the excess oil from the PCV system before it was repaired is what killed the cats on my 2012. BOTH were bad and the one right off the engine was broken apart.


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