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Discussion Starter · #1 · (Edited by Moderator)
Ive been getting a p0420 code since ive had this truck, so april 2021. Ive run the diagnostic tests and the o2 sensors look to be sporatic as seen in the attachment. I know the sensors are supposed to fluctuate between.1v and .9v on both banks for s1, but the s2 sensor should stay steady around .4v.

What is really bothering me is the smell of sulphur coming into the vehicle while driving. Its almost unbearable.

Do you think by replacing the 4 sensors i might manage to rid the smell? As i have read that the sulphur smell is coming from burning too rich.
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Sorry, forgot to mention. 2011 gmc acadia slt with 220000 km.
It really may do he trick replacing 02 sensors after that many years and miles of use.
O2 sensors can become "lazy" in that they respond slower than they should or even give erroneous readings.

So, yes, IMO and many others, replacing the O2 sensors may be a good idea at this time. But you could also take it into a shop that has more comprehensive diagnostic equipment and they may be able to act on your assumptions and the sulfur smell.
 

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What is really bothering me is the smell of sulphur coming into the vehicle while driving. Its almost unbearable.
That could indicate there's an exhaust leak beneath the vehicle. Exhaust leaks can also interfere with O2 sensor readings.
 

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That could indicate there's an exhaust leak beneath the vehicle. Exhaust leaks can also interfere with O2 sensor readings.
The only thing that steers me away from the idea of a exhaust leak is there is no audible sign of one at all. Not even the famous and subtle phoot phoot phoot sound.
 

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The only thing that steers me away from the idea of a exhaust leak is there is no audible sign of one at all. Not even the famous and subtle phoot phoot phoot sound.
That may be, but sometimes the flex connector on vehicles just ahead of the main exhaust system can start to crack and leak sometimes with little noise.
A search for " sulfur smell inside car " on the web may reveal some further ideas.
 

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Ive been getting a p0420 code since ive had this truck, so april 2021. Ive run the diagnostic tests and the o2 sensors look to be sporatic as seen in the attachment. I know the sensors are supposed to fluctuate between.1v and .9v on both banks for s1, but the s2 sensor should stay steady around .4v.

What is really bothering me is the smell of sulphur coming into the vehicle while driving. Its almost unbearable.

Do you think by replacing the 4 sensors i might manage to rid the smell? As i have read that the sulphur smell is coming from burning too rich.
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If this were my car I would start at the other end. Is soothing telling your fuel injection to run rich? Start with cleaning or replacing the mass airflow sensor. Make sure the throttle body is clean and free of oil.

I would ask if your injection is sending too much fuel. Start at the other end. Is your mass airflow sensor clean or new, is your throttle body free of dirt and oil, are your intake valvesclean, are your injectors clean
 

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A failed cat would also be my first thought, which is most often the trigger for a P0420.
Not a bad idea to check what's happening upstream. Too many folks have changed a catalytic converter because of the code and have seen the code return, even when the replacement catalytic converter is an OEM part.
 

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Not a bad idea to check what's happening upstream. Too many folks have changed a catalytic converter because of the code and have seen the code return, even when the replacement catalytic converter is an OEM part.
I was thinking back to my only experience with a P0420. It was on my son's '96 Camaro. It had close to 200k miles.

New cats resolved the issue.
 

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I have a 2008 gmc acadia slt 166 mile with a po420 code replace the catalytic converter the left side and the front one and the flex pipe and the spark plugs don't have a smile car runs good wind the check engine light come on runs a Lil like its losing power but still picks up I put after market catalytic converter on it because they said I need them do any body no what I can do next .Help .Thanks
 
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