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Discussion Starter · #1 ·
Ever heard of this code? well I got hit with it a while back and it has been coming and going for sometime. Some details about my traverse.. 2010 LT AWD, 258,751 miles. same engine and transmission. added tow package many years ago (bigger tranny cooler, upgraded fuse block tow wiring harness)
I have drained and filled tranny handful of times since then.. I believe changing tranny fluid every year is in order for these cars but the experts may differ. I have change spark plugs, intake manifold gasket, coils...
Now comes the question and i do have a few: why does the P0420 comes and goes? Only comes on because i have reach a quarter tank of gas or when i fill up. Bad gas? probably. Do those two scenarios happen every time? matter of fact no, once every two 2 to 3months. How do i clear it? Replaced gas cap with new one, add fuel treatment or drive the crap out of it. I don't clear the code at all but when I do check it while the CEL is off, code reader doesn't see anything. I use FIXD reader and the app. i find that it is accurate but experts may disagree.
Yesterday i did use the CRC Intake Valve cleaner and that cleared the light on its own. I have added a bottle of the Techron concentrate plus... we'll see. I have changed the purge valve two weeks ago due to P0455 and that also cleared the light on its own. My wife drove the car nearly a thousand miles and no CEL.
Here are the other sets of questions and statements: I am not big on tearing out a CAT or replace O2 sensors because i have seen many who've done so on this forum or the Acadia hangout and they still have the P0420 code. Why should I do it when it isn't a conclusive fix?
These many miles i am hesitant to take any deep dive surgical fixes especially since my traverse have never lost power! does not hesitate and I tow a lot with the car. if you've my towing package upgrade write, i mentioned pulling a popup but it is a very heavy popup easily near 4000lbs. I have changed engine mounts also. I am willing to fix it at all cost and even replace the cats if that is a definitive fix.
I love this car and i think maybe one of the lucky ones to have one these last this long but I will take another traverse in a heart beat! I like this thing so much, I am seriously considering buying another engine and just slap it on and go for another 250K miles. Guess what, this engine still sound and feels fine to me.
I welcome any suggestions and I am willing to try anything... after all what do i got to lose? My favorite car in the world, which is ALOT!!!
 

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O2 sensors get weak and slow responding. Especially at your mileage.
I changed my front O2 sensors in my Tahoe and got back 2 mpg. 100k miles on them. Yeah 2 mpg is no big deal but 2 in something that used to get 18 mpg is a big deal.
My sensors looked fine on my PC scan tool, no codes but they definitely had issues. Tailpipe is less sooty now also.
When my fleet is ready for spark plugs the front sensors get changed now also.
I'll wager slow upstream sensors also a silent killer of cats also by running them richer over time.
 

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I had the same code for a while now and more codes were coming in saying fuel mixture was too rich. Just this past Monday (3/22/21) I changed all 3 cats. I know the 3rd one isn’t in any loop but wanted to get rid of the check engine light to pass inspection. Changed the cats and the light is now gone. I did not change the O2 sensors. I did change the cats before and ordered them from an aftermarket place and they didn’t last long and were smaller and weighed less. This time I bought OEM online from a GM dealer. So far so good. The cat by the firewall (bank 1 I believe) is a little trick but doable. I drove it up on 4 ramps and had ample space to work.

Hope this helps
 

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Discussion Starter · #4 ·
I was looking at O2 Sensors and I saw a deal on ebay for 4 of them. I believe they are identical sensors. Question is, are there specific sensors for upstream and downstream? can a downstream sensor go into an upstream? Difference?
 

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on the 2010 traverse-- the downstream have a different part # than the upstream.
heres a post I made yrs ago when I changed out all 4 at 100,000.
I Listed the part # for the units I bought- BOSCH.
I also list what they would have cost at different stores/online.
I Just checked- and 1 sensor has changed part number. They are also a little cheaper.



incidently, just yesterday I ordered 4 oxygen sensors for my 2013 Equinox 3.6 V6- on this vehicle- the same sensor part # is used in all spots- which surprised me. Nearing 99,000
 

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Sensors report what the cats are doing. Replacing sensors are step one and if cats do need replacing then new sensors are needed anyway. O2 sensors are wear items, very often folks will pull out a old sensor and see it's caged end melted away. Use AC Delco sensors for zero issues, other brands can be problematic. Rule of thumb is to always use manufacture sensors for zero issues no matter the brand of vehicle.
 

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Discussion Starter · #9 ·
I ordered Bosch sensors, which I believe are the OEM "ACDelco" currently in there. Someone correct me if that's wrong. 16088 and 16089
Question before I lose my cool... I ordered Bosch 16089 from ebay and they sent me Bosch 16088. Am a little frustrated but I also understand those two parts are interchangeable, is this correct?
 

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Discussion Starter · #10 ·
Question before I lose my cool... I ordered Bosch 16089 from ebay and they sent me Bosch 16088. Am a little frustrated but I also understand those two parts are interchangeable, is this correct?
 

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I dont think they are interchangeable.

Rock auto shows the new upstream as---

BOSCH 16454 Actual OE Oxygen Sensor
Upstream
and 16089 as the downstream,

What is interesting is that on Amazon, I looked up the part- and it says it does NOT fit my 2010 Traverse.
I guess the new updated part # is the new 'fit'.
 

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Discussion Starter · #12 ·
Update: I replaced all O2 Sensors three weeks ago and I was thrilled because i drove a few hundred miles with no CEL. Well today it came back and needless to say i was deflated. Yes my sensors were BOSCH.
I am dreading having to replace the CAT. If it was an easy job, i would do it in a "Traverse minute"!!! Here's the thing i have not experienced any loss of power and the vehicle drives and sounds great. The CEL engine light goes off and ON. When it is off and i scan for a CODE there's usually nothing to find. When add Techron concentrate, it will go away! when I add SEAFOAM it will also go away. I am driving on a full tank of Gas when i noticed it. but it also has come on at below quarter tank. I have heard @rbarrios say he gets this code as well and he uses Techron Concentrate to deal with it. Mr. rbarrios, have you raplaced your CATs and why not? This is my dilemma: Should I replace the CATS or not? I am looking for honest feedback and advise.
 

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My CEL has never set.
I do get some light misfires that I can feel- and my scanner will show 1-10 misfires. but not bad enough to set the CEL.
I do run Techron 1 tankful before an oil change.
I have NOT changed my CATS- because they have not failed.
I Live in California- where they have strict Emissions.
We have to use OEM cats when they fail. We cant use the universal types.
To me its easier to change plugs and O2 Sensors to keep the CATS in working order.

There is a product that is sold- its called CATACLEAN. its supposed to clean catalytic converters.
 

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To me its easier to change plugs and O2 Sensors to keep the CATS in working order.
2x, better to have the first sensors that control fuel mixture in top shape as not to overload and shorted the life of expensive cats.
 

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Discussion Starter · #15 ·
So i have resolved the P0420 with the O2 sensors. when the codes cleared, they never came back. However, there are new issues: P0455/P0497. both these codes point to gas cap and fuel vapor issues. I have replace two caps, I have replaced the purge valve solenoid and also the vapor valve on the tank. I have done a smoke test at home and found no leak. I have ordered a charcoal canister and a tank pressure sensor and will install that tomorrow. If those last two parts don't solve it, then i don't know what. let me know if you have any ideas.
on a side note, i am in the market for a another traverse. I saw one today that has front wheel drive with snow mode. any opinions on the snow mode? can i substitute allwheel drive for snow mode?
 

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Discussion Starter · #16 ·
Hello Everyone,

I would like to revive this post and get more input. Someone told me the CATS on these vehicles don't go bad as quick as we think. Rbarrios mentioned that the sensors do get lazy and I believe that. my situation has evolved a little bit. Now that said... My CEL comes on after gas fill up. When the level goes down to 3/4 tank or around there, the light comes on like clock-work. if I clear it, it will come back on around 1/4 tank. is there a sensor that checks the fuel level in those two stages other than the guage? could this be a fuel pressure sensor issue? i got a seal on the original gas cap and believe it or not the light went away on its own. but it did come back on. my gut feeling is i have gas cap issue or the more likely issue is some other sensor.

I know my car is old but i trust that i can get quite a bit more from it. The engine on idle is almost inaudible. The car still has the feel of 0-60 in 1 minute! The gas mileage is still awesome.
What do you think?
 

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Only thing I know of that is fuel level dependent is the EVAP monitors will not run when over 3/4 or less than 1/4 tank of gas. O2 run when warmed up and into closed loop running.
Have you run a scan of all 4 code families to see if any are present outside of just the P codes?
 

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There is a p0420 thread on the acadia forum now.
 
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