GMC Terrain, Equinox, and SRX Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
2011 Terrain 2.4L. 135,000 miles.
Cat has about 15,000 miles on it, new downstream and upstream 02 Sensors.
Engine does consume some oil. Need to clean port in intake.

I have cleared the code with cheap scanner, removed all ecm fuses but the scanner still shows code P0420, but the check light does go off, with scanner. Would this be a Engine Control Module problem and how to verify if possible.

My next step is to disconnect battery and see what happens. I am also waiting for a borescope to arrive so I can inspect the Cat converter condition.

Any advice would be greatly appreciated

Larry
 

·
Registered
Joined
·
56 Posts
You can turn that code completely off with an HP Tuner. If you are in the Houston area I can do that for you. Would take probably 2 credits at about $49 each. Until that code is off it probably won't pass inspection.
 

·
Registered
2011 Equinox 1LT V6 3.0L
Joined
·
3,996 Posts
A 2011 2.4L consuming oil with a P0420 at 135,000 miles I’d bet was a Catalytic Converter damaged by the oil, but you say it’s only got 15,000 miles on it, so did you replace the Converter, and with what brand? If that’s a GM Converter I’d doubt it’d be gone that quickly.

Also - what brand of O2 sensors did you install, and what are they showing for values? You’ll need a slightly better than “cheap” scanner to read them. My $80 Harbor Fake scanner can read them, for example.

UPDATE:

Check out this “5-minute fix”. The guy installs an “elbow” on the O2 sensor (to back it out of the exhaust stream a bit):

 

·
Registered
Joined
·
779 Posts
Yea the gm cats are actually really good idk why people always get that code probably a really sensitive computer to keep up with emissions, idk for the California gm cat it's over 1000$ the oil carbon should burn off but if the car is constantly burning oil replacing the cat would maybe fix the code for a few months but fixing the oil burning / new pistons and rings could totally clear out the converter.
 

·
Registered
Joined
·
1,157 Posts
Colt those elbows have been around for a while now. They first showed up for 5.0 Mustangs when guys did high flow cats or eliminated them.
 
  • Like
Reactions: Colt Hero

·
Registered
Joined
·
779 Posts
U can just use exhaust sealer sludge on the 02 seal every hole but the top works the same anything to get the second 02 to read steady .45v or under .
 

·
Registered
2011 Equinox 1LT V6 3.0L
Joined
·
3,996 Posts
Colt those elbows have been around for a while now. They first showed up for 5.0 Mustangs when guys did high flow cats or eliminated them.
So ... they work (?) ... or it’s just hit and miss?

And then - what happens if this is noticed in an Inspection? Might you get a Rejection Sticker for a “modification affecting Emissions “?
 

·
Registered
Joined
·
1,157 Posts
Don't know if they work, they first came out for Fox body 'stangs back then.
Most inspections just look to see if a cat is in place and not what the O2 sensor is doing. Here in NJ they have a under car video camera when they drive it to the OBD plug in station. They also just use a mirror on a stick if camera isn't clear.
 
  • Like
Reactions: Colt Hero

·
Registered
2011 Chevy Equinox 2.4L (LAF) LS FWD
Joined
·
49 Posts
If that P0420 code happens before 120,000 miles they will replace it under a service bulletin, but the oil will burn out the next one in due time, I see that you're way past the 120 mark, so the best thing to do is change the rings, etc., and hope that it will clear the cat out over time by burning it off, but until then you'll have to dodge the state inspection "police", lol....
I got lucky and they replaced mine for free under that service bulletin, but I haven't changed my rings, and I've gone about 35 thousand miles since they replaced it, and I'm hoping to catch a break very soon to replace the rings myself, I did install an oil/water separator and I think that's buying me a lil time on my cat, and I would highly suggest you sing the same whether you replace the cat or not, it'll help keep the intake manifold and combustion chamber somewhat cleaner.
Moving the sensors out of the line of exhaust isn't a good thing if you like you're engine to run the best it can, in other words when something really goes bad you'll never know cause it can't get a good/true reading or of the line of the exhaust....
Keep me updated please, that way incase something goes wrong on mine and I'm not catching what's really wrong with the engine, thank you and be safe!
P.S.- check if the cat has a year/mileage warranty on it before dumping money on another one, hopefully it's just a faulty cat....

2011 Terrain 2.4L. 135,000 miles.
Cat has about 15,000 miles on it, new downstream and upstream 02 Sensors.
Engine does consume some oil. Need to clean port in intake.

I have cleared the code with cheap scanner, removed all ecm fuses but the scanner still shows code P0420, but the check light does go off, with scanner. Would this be a Engine Control Module problem and how to verify if possible.
P.S.- check if there's a year/mileage warranty on the new cat and have them check it before you dump money in that direction, if possible....

My next step is to disconnect battery and see what happens. I am also waiting for a borescope to arrive so I can inspect the Cat converter condition.

Any advice would be greatly appreciated

Larry
 

·
Registered
Joined
·
1,157 Posts
After cat sensor has no effect on engine performance, it's only there to monitor the cat's efficiency and nothing else.
Pre cat sensor, the ones closest to engine are the primary sensors for fuel management.
 

·
Registered
2011 Chevy Equinox 2.4L (LAF) LS FWD
Joined
·
49 Posts
You are right, it doesn't have any direct effect on the engine but you'll never know if the cat is doing its job, and if the cat isn't working properly then it can cause the engine to run poorly, and even cause back pressure if it is not burning off the carbon properly.
So no, directly it doesn't, but indirectly, yes it does....

After cat sensor has no effect on engine performance, it's only there to monitor the cat's efficiency and nothing else.
Pre cat sensor, the ones closest to engine are the primary sensors for fuel management.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #14 ·
Update.
I replaced exhaust manifold still got code. Finally determined by vacuum cleaner and soapy water the upstream o2 sensor crush gasket was leaking causing problem .Replaced o2 sensor and code disappeared.
 
1 - 14 of 14 Posts
Top