[dumbo]

Hi all. I have a 2013 Terrain, approx. 110,000 miles. I took it in to be serviced at a local GMC dealership, for two recalls and an oil change. One of the recalls was a replacement of the rear oxygen sensor. The next day the check engine light came on and has stayed on ever since. I made an appointment to have this checked out, but because the dealership had double booked appts., they couldn't do anything at that time, other than check to make sure it wasn't something catastrophic. The gal said it was showing a code 0420, "catalyst system efficiency below threshold bank 1."

I made another appointment, which is coming up this week, to check this out further. I haven't had any issues with the vehicle, and frankly, I'm suspicious of the timing of this. For the CEL to come on so soon after a servicing just seems too coincidental. Am I wrong to think this? Is it possible that when replacing the rear oxygen sensor they fouled up something else?

I realize I am asking for input, with very little information given, I'm just trying to educate myself in case they say I have to replace the catalytic converter, etc. (I don't have a history with this dealership, as I am new to the area, and I guess I'm being a bit paranoid about being taken advantage of).

I appreciate any insight, and will follow up here after the appointment, with what they said. Thank you again!

 

[RIT333]

I would also blame the dealer, since they touched it last.

 

[rbarrios]

Could it be a new rear O2 sensor has actually detected a problem that the previous one had not.
The recall was done because that oxygen sensor may have been sending bad info to the computer.
The new updated sensor has most likely detected an emissions problem.

 

[hron61]

Interesting.
This is the first time i've ever heard of a recall on a rear 02 sensor.
Is the sensor repair covered by gm?
Rbarrios post totally makes sense.
Hopefully its not a bad cat and its just a bad or a weak 02 sensor.

 

[dumbo]

Thank you all for your replies thus far. Hron61 I agree, Rbarrios' post makes sense to me as well. I hadn't thought of it in those terms.

Yes, the sensor recall/replace was covered by GM.

Ugh, I hope I'm not looking at replacing the cat.. I will update after the appt., which is tomorrow morning.

 

[rbarrios]

Google this txt. Should give the pdf.

October 1, 2020 Subject: N192268180 - Emission

 

[Ebeo1]

@dumbo

Try Lucas Upper Cylinder Lubricant with Injector Cleaner and Fuel Conditioner. I have been using that in my car and also taking it out on the highway for an hour long drive.

I'm not an expert and can't tell you why this works for me, but the theory is to use your exhaust heat to burn out the soot in the catalytic converter.

 

[dumbo]

Per the GM Dealership after my appointment today - "Catalyst has degraded and is no longer operating to specs. Special policy 'blah blah blah' may cover catalyst if due to excessive oil consumption." So, they topped off the oil and I am to return in 1000 miles to see how much oil the vehicle has consumed. If it is excessive, a new catalytic converter may be covered by GM. We shall see, I guess.

Again, thank you all for the input. I appreciate it!

 

[crashmonkey]

So, they topped off the oil and I am to return in 1000 miles to see how much oil the vehicle has consumed. If it is excessive, a new catalytic converter may be covered by GM. We shall see, I guess.

Do you have the 2.4L engine? If so, and if you hadn’t had the pistons and rings replaced under the class action lawsuit 2 years (ish) back, you probably are getting excessive oil consumption. Cats, exhaust manifold, etc will continue to degrade quickly if they don’t fix the root cause. Keep your appts, show up right at 1000 miles, and watch your oil levels in the meantime.

 

[UniqueOx]

Excessive oil blowby could def ruin a cat if it goes on long enough. Does your Terrain use a lot of oil? Coolant can also ruin a cat. Just for giggles, you might want to check for coolant consumption too or other signs of a coolant leak into the combustion chamber. I hope you don't have a blow head gasket or crack. If you do need a new cat, I hope GM pays.

 

[Ebeo1]

Here is a similar thread, the author replaced the catalytic converter himself.

Intermittent CEL

P0420 is the intermittent code. Replaced both O2 sensors about a month ago. The light comes on for about a day and then goes off again for another 500+ miles. This has happened twice now. Perhaps the catalytic converter is on its way out. Perhaps it is an electrical issue. Any input is...

www.terrainforum.net

 

[Tracye P.]

My 2010 Terrain has had the check engine light on since new, per the first & only other owner. No clue why, even dealer mystified in past. Now I can't pass inspection with a P0420. In the 2 yrs I've had, it has consistently showed a dif code when light gets cleared then comes back on. I'm leery of catalytic code because she installed a new one in 2019. And various other lights randomly turn off and on. I'm convinced it's somehow an electric issue, but No one will listen to me. They just want to charge me mega bucks. And dealer after checking it out wants to charge $5,000 to correct all involved and my car has FOUR cats! Really?!
I wish you luck but be careful. This car has sucked close to $6,000 from me in 2 yrs.
Will hopefully never have to buy a GM car again.

 

[lou-in-usa]

Don't fool around, read my posts in this thread:
https://www.terrainforum.net/threads/p0420-its-not-the-cat-or-02-sensors.24201/post-318061
But in your case it could be the Cat, but check it yourself unless you're under warranty...and if it is your Cat, make sure whoever replaces it cleans out all the debris from the first Cat's disintegration, at the screen of the second Cat! Otherwise you will overheat your new Cat and ruin it within 6 months, and get bad performance while you ruin it.

 

[swisscheese]

Hi all. I have a 2013 Terrain, approx. 110,000 miles. I took it in to be serviced at a local GMC dealership, for two recalls and an oil change. One of the recalls was a replacement of the rear oxygen sensor. The next day the check engine light came on and has stayed on ever since. I made an appointment to have this checked out, but because the dealership had double booked appts., they couldn't do anything at that time, other than check to make sure it wasn't something catastrophic. The gal said it was showing a code 0420, "catalyst system efficiency below threshold bank 1."

I made another appointment, which is coming up this week, to check this out further. I haven't had any issues with the vehicle, and frankly, I'm suspicious of the timing of this. For the CEL to come on so soon after a servicing just seems too coincidental. Am I wrong to think this? Is it possible that when replacing the rear oxygen sensor they fouled up something else?

I realize I am asking for input, with very little information given, I'm just trying to educate myself in case they say I have to replace the catalytic converter, etc. (I don't have a history with this dealership, as I am new to the area, and I guess I'm being a bit paranoid about being taken advantage of).

I appreciate any insight, and will follow up here after the appointment, with what they said. Thank you again!

I am assuming you have the 2.4. My equinox started going through oil about 90,000 miles, 127,000 now. My mechanic friend told me to stop using synthetic and run high mileage oil which generally comes in a synthetic blend mix. I went with a 1040 and it has decreased my oil usage to about 1/3 of what it was using synthetic. My light with the 420 code comes on anywhere from 50 to 400 miles. I just passed emissions so I’m good for two years. I’ll just keep clearing the code, hoping it eventually stays off now that I have the Oil consumption under control

 

[Ebeo1]

I went with a 1040 and it has decreased my oil usage to about 1/3 of what it was using synthetic.

Do you notice a change in gas mileage

 

[MexicaninMaine]

Hi all. I have a 2013 Terrain, approx. 110,000 miles. I took it in to be serviced at a local GMC dealership, for two recalls and an oil change. One of the recalls was a replacement of the rear oxygen sensor. The next day the check engine light came on and has stayed on ever since. I made an appointment to have this checked out, but because the dealership had double booked appts., they couldn't do anything at that time, other than check to make sure it wasn't something catastrophic. The gal said it was showing a code 0420, "catalyst system efficiency below threshold bank 1."

I made another appointment, which is coming up this week, to check this out further. I haven't had any issues with the vehicle, and frankly, I'm suspicious of the timing of this. For the CEL to come on so soon after a servicing just seems too coincidental. Am I wrong to think this? Is it possible that when replacing the rear oxygen sensor they fouled up something else?

I realize I am asking for input, with very little information given, I'm just trying to educate myself in case they say I have to replace the catalytic converter, etc. (I don't have a history with this dealership, as I am new to the area, and I guess I'm being a bit paranoid about being taken advantage of).

I appreciate any insight, and will follow up here after the appointment, with what they said. Thank you again!

Code came up recently on mine. Sensors were good so I figired it needed a new cat. It did need a new one but turned out my exhaust manifold was cracked too.

 

[dumbo]

Excessive oil blowby could def ruin a cat if it goes on long enough. Does your Terrain use a lot of oil? Coolant can also ruin a cat. Just for giggles, you might want to check for coolant consumption too or other signs of a coolant leak into the combustion chamber. I hope you don't have a blow head gasket or crack. If you do need a new cat, I hope GM pays.

Thanks for the thoughtful response Ox. To be honest, I'm unsure whether or not my Terrain uses a lot of oil. I follow the old rule, of checking my dipstick when I fill up, and I would say that about half the time it is down some, so I top it off. My husband drives the car too, and I don't know how often he puts oil in her, so....
I guess I'll find out when I take it back in to the dealership at the 1,000 mile point.
How would one check for excessive coolant consumption? What would be other signs of a coolant leak?
Thank you again for replying.

 

[dumbo]

Do you have the 2.4L engine? If so, and if you hadn’t had the pistons and rings replaced under the class action lawsuit 2 years (ish) back, you probably are getting excessive oil consumption. Cats, exhaust manifold, etc will continue to degrade quickly if they don’t fix the root cause. Keep your appts, show up right at 1000 miles, and watch your oil levels in the meantime.

Yes, Crashmonkey, it's a 2.4L engine. I didn't have the pistons and rings replaced, I was unaware of the class action lawsuit. I'll have to google that. Thank you for your reply.

 

[dumbo]

Thanks to all who have responded. I don't have anything new to report, re: the Cat., as I have not yet returned to the dealership for the 1,000 miles oil consumption test.

However, there is a new issue now. My husband was replacing the spark plugs, and found oil in the #3 spark plug well, sigh. I'll ask the dealership about this when I take it in. In the meantime, I wondered if anyone here could enlighten me a bit about what this might mean, given the Cat. issue?

Thank you all!

 

[crashmonkey]

However, there is a new issue now. My husband was replacing the spark plugs, and found oil in the #3 spark plug well, sigh. I'll ask the dealership about this when I take it in.

Edit: grammar

I’m so sorry for the late reply. I was not receiving notifications. I hope you have called to report this or brought the vehicle back in. You may have found by now that your piston in #3 (at the very least) is very likely going bad and you blew a seal. Your oil is leaking out and is going to cause a lot more damage if it hasn’t already. This will likely (and hopefully) be enough to push them toward “the bad design caused excessive oil consumption which…..destroys pistons” and a repair in lieu of continuing the test. This is a known issue and all over these forums. Stick this forum in their face and they can’t deny it. You can read hundreds of posts over the years about this issue.

Also see: Frozen PCV causes excessive crankcase pressure which blows your rear seal. People are paying from $1500 (me) to as high as $3200 on repairs because of the havoc the PCV causes. I’d highly recommend buying the FC219 vented oil cap and having your PVC valve cleaned out. You’re now going to need to check your throttle body for buildup and if it’s as bad as mine was it will be full of oil and yellow sludge. Do not attempt to service the throttle body yourself before reading how to do it properly, or else you can be lazy like me and throw a new one in. After over $3k out of pocket at that point I figured, what was another $100? 🙄

Also search: Cracked exhaust manifold; Replace catalytic converter; all due to the same issues as above.

Just for fun, here’s a little background on my history with GM: I traded in my Terrain one year ago after over $5k cumulative out of pocket repairs, not including the class action piston/ring replacement, and it was finally running a lot better, but not 100%. I could never trust it again. I sued GM in ‘08 for a bad engine in my Cobalt. They had the car in the shop for well over 30 non-consecutive days working on the issue, replaced the engine, it still didn’t run. I paid off the loan, traded it in, bought a used Saturn Vue (GM) 🤦🏻‍♀️ Great little car but almost killed myself in MN winters with no ABS or traction control. Traded for a Mitsubishi which was the most amazing vehicle (never had a problem) until I had to go bigger again, so I went back to GM for an older Tahoe. Awesome truck, but still lots of money poured in for regular repairs at that age and mileage. Downsized a few years later to the Terrain which became the worst nightmare ever. The guy tried to talk me into the V6 but it was too much, so I bought the 2.4L and they practically gave me the lifetime warranty for free. Now I know why! Guess what I traded in my Terrain for? A Tahoe! 🤦🏻‍♀️ You’d think I’d learn. 😊 I bought a good one though. Did my research this time for the exact used model because guess what issue some of these Tahoes (not mine) have? If you said, “Excessive Oil consumption” you win!