Issues after 70k miles

TxSilver · November 9, 2018

So I had a check engine light popup a week ago and dealer replaced all 4 banks of sensors and the catalytic converter, totalling over $1,500 in repairs (covered by extended warranty). Truck has almost 70k miles and the extended warranty is good for another year and/or 5k miles.

With this in mind, have you guys had any major issues on your trucks between 70k and 100k miles? I'm not totally convinced with the 2019, so I'm thinking about keeping the truck until the next Tahoe comes out.

Brianibew · November 9, 2018

Seems like they just threw a bunch of parts at it with hopes it fixed it. I have a hard time believing all the O2 sensors went bad at once.

TxSilver · November 9, 2018

Originally, they just replaced 2 but light came back on, so the replaced the other 2. Overall, i had to take the truck 3 times to the dealer to get it fixed.

And guess what, they tried to blame the K&N filter for it. At the end I agreed for them to put a new one in.

btj_z71 · November 9, 2018

At 64k now on my 2014 and the only major issue was the AC compressor blowing up at 34k. All else has been good. Haven't had so much as a light bulb go out yet.

1SLOW1500 · November 9, 2018

That is bs there are 2 Banks and 4 sensors. Up stream and down stream. Checking the codes should show down stream issues if cats where bad. I would guess something larger in the engine commanding fuel trims.

Edited November 9, 2018 by 1SLOW1500
Type o

TxSilver · November 9, 2018

First code was P2097...

1 hour ago, 1SLOW1500 said:

That is bs there are 2 Banks and 4 sensors. Up stream and down stream. Checking the codes should show down stream issues if cats where bad. I would guess something larger in the engine commanding fuel trims.

1SLOW1500 · November 9, 2018

First code was P2097...

And there it is bit fuel doesn't magically show up in the cats. The pcm is commanding it. So real question is why. On these trucks there are about a thousand reasons. As so many sensors can chand the fuel,idle, and air. I would request a full sel print out. It can be two pages. It will show history as well. Then I think I would pay the low cost of a good independent shop hooking up a scan tool and going through all the systems. He may come back with a issue. Then you can still have GM fix it.

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TxSilver · November 10, 2018

26 minutes ago, 1SLOW1500 said:

And there it is bit fuel doesn't magically show up in the cats. The pcm is commanding it. So real question is why. On these trucks there are about a thousand reasons. As so many sensors can chand the fuel,idle, and air. I would request a full sel print out. It can be two pages. It will show history as well. Then I think I would pay the low cost of a good independent shop hooking up a scan tool and going through all the systems. He may come back with a issue. Then you can still have GM fix it.

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It's been working fine for over a week, so the issue is fixed as far as I'm concerned. If the check engine light comes back again, I'll just take it to the dealership.

Grumpy Bear · November 10, 2018

40 minutes ago, 1SLOW1500 said:

And there it is bit fuel doesn't magically show up in the cats. The pcm is commanding it. So real question is why. On these trucks there are about a thousand reasons. As so many sensors can chand the fuel,idle, and air. I would request a full sel print out. It can be two pages. It will show history as well. Then I think I would pay the low cost of a good independent shop hooking up a scan tool and going through all the systems. He may come back with a issue. Then you can still have GM fix it.

Question. Could a bad pre cat O2 sensor trick the ECM for more fuel and be pickup up by a functional post cat sensor?

1SLOW1500 · November 10, 2018

Question. Could a bad pre cat O2 sensor trick the ECM for more fuel and be pickup up by a functional post cat sensor?

Yes but that would throw a code as the truck would be confused to why one bank is lean as it cant add fuel to one bank like that. So you would need 2 bad up stream o2,baro, iat,engine temp ect.. to command fuel trim. All things that if to far out of spec should throw code. But there are solf codes,dont set off light. So a complete history report is the only way to attempt to find the issue.
Hell maybe a miss fire or bad injector. As I said could be a thousand things even if all physical parts are good.

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1SLOW1500 · November 10, 2018

Another thought. from another site.

When carbon issues started coming up on GM DI motors GM started carefully suggesting a "decarbon" type cleaner be run through the intake pretty often. Then they said uh, maybe not....as some were cooking their cats during the process. If done often enough the valves and pistons won't get too much build-up so the cheap drip style method through the intake can be used carefully. I have heard of lots of guys having dealers pull their intake and wallnut blast the valves. Most of these rigs that I work on are run hard all of the time and still don't have a build-up at over 75k. There is another fleet that will not get run so hard but they are not getting driven enough to have any kind of result. It will probably be interesting to run a can of Seafoam or similar through it and see what you get (usually smokes really bad for a while if there was much build-up).

Grumpy Bear · November 11, 2018

9 hours ago, 1SLOW1500 said:

Most of these rigs that I work on are run hard all of the time and still don't have a build-up at over 75k.

GDI correct?

1SLOW1500 · November 11, 2018

GDI correct?

Yes that is what is referred to.

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Grumpy Bear · November 12, 2018

On ‎11‎/‎10‎/‎2018 at 9:59 AM, 1SLOW1500 said:

Most of these rigs that I work on are run hard all of the time and still don't have a build-up at over 75k.

Point, set and match. Thank you.

Edited November 12, 2018 by Grumpy Bear

Ed S · November 17, 2018

My 14 Sierra started having failure issues at 40,000 miles. Heated seats, door lock actuators failing etc. Failing after the 3 year warranty ran out of course. Consider yourself lucky you have got to 70,000 without any issues. They want to build their trucks as cheaply as possible but yet want the most they can get selling them to you. Just my opinion. Good luck!