P0420 Code – 2013 Chevy Equinox 2.4

[Andy Knight]

Hi all,

My 2013 Chevy Equinox with the 2.4L is showing a P0420 code. The code first appeared a few weeks ago, turned itself off after a few days and then returned. I took it into a trusted shop and they recommended to start with replacing the 02 sensors. They wanted an arm and a leg to do the job so I replaced them myself using GM/AC Delco sensors. (I’m fairly mechanically inclined and have a good assortment of tools. Most of my experience is with older vehicles and I don’t have access to high tech scan tools or experience with modern vehicle diagnostics but I’m more than capable of replacing parts and doing basic repairs). After a few days of normal driving the code turned itself off and I assumed the problem was solved. Now, another two weeks or so have passed and the CEL is back on showing the same P0420 code. Other then the CEL the car is not exhibiting any other symptoms, e.g. no noticeable difference in fuel economy or loss of power.

Shortly after we got the vehicle we experienced the classic oil consumption issues. We had the piston rings done etc.. in 2019 at a GM dealership (and were lucky to be reimbursed). Since the fix we have not experienced any other oil consumption issues. My best guess is that the excessive oil consumption in the past damaged the catalytic converter and it is just now giving out. I’m guessing the next move is to replace the catalytic converter but I was hoping for some advice before I go off and replace expensive parts. When possible I like to diagnose problems rather then just be a parts replacer!

Thanks so much in advance for all the help!

-Andy

Topic

[Dave Tidman]

An oldie but a goodie to watch: https://www.youtube.com/watch?v=9VZ5K8n5jj0

A scanner with live data may help.

[Andy Knight]

Thanks for the reply!

I checked out the video you linked but I’m afraid the results didn’t bring me much clarity. I tried both methods Eric demonstrates and seemed to get different results. I used my scan tool to check the live data from the 02 sensors and the upstream sensor oscillated rapidly as Eric shows in the video while the downstream sensor pretty much hung consistently around .8 volts. It moved a little but the changes were slight and not rapid – much closer to how Eric shows it on the Odyssey rather than his Subaru.

I also tried using the temp gun to check inlet and outlet temperatures. I recorded very similar temperatures (between 400-500 degrees) at the inlet and the outlet. However, I’m not totally sure of the validity of these results as on the Equinox the catalytic converter sits right up under the exhaust manifold tucked back agains the firewall i.e. it’s very difficult to get a temperature gun in there and be sure that you’re getting a reading off of the inlet of the catalytic converter and not off the body of the converter itself, a heat shield, the exhaust manifold, or something else in the vicinity.

I’d hate to replace the converter without verification but I’m not sure what else (other than the 02 sensors I’ve already replaced) would cause the P0420 – especially given that I know this vehicle suffered from oil consumption issues in the past.

Thanks for the help in walking me through this!

[Author]

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