SEL light discussion (what's causing it?)

[kmeleon]

I have a 2021 GMC sierra elevation 5.3L. I bought the truck Xmas 2020 and now has 5800 miles on it. The truck was built in 10/20. I started having issues around 1300 miles (1/21) and I continue to as of yesterday. I've been reading these forums and multiple Facebook groups and there seems to be a few things going on that cause these rash of lights. There's what seem to be what gm describes as "phantom" SEL lights, meaning the truck ecm is sensing a misfire but there isn't one according to them. It happens for no reason. They claim to have a ecm update but from what I've read I don't think it will fix the issue. We shall see. The 2nd issue is the SEL light flashes or goes solid accompanied by a bunch of other lights and the truck running rough. This is the dreaded lifter failure, it sometimes destroys the entire engine with it. This I haven't experienced... Yet. My truck does fall into the faulty lifter window  laccording to the build date. We shall see. 

 

I want to discuss problem #1.... the random flashing SEL and see what others have noticed. I've probably had it happen over a dozen times, it's been to the dealer approx 5 times now. I know how to cause the light, I can't make it happen on cue but if given a few days I can make it happen. Heres the lowdown... Basically the truck can't be cold. It also has to be in "Drive", not "L" (more on that later) For example, I will drive home for lunch and my truck will sit for 30 minutes or so. I pull away from my house driving 10-20mph with light acceleration and braking thru the neighborhood. Most of the time it will happen immediately after coming to a stop and then turning left with light acceleration onto a certain street within a minute of starting the truck. The truck when pulling away will have a slight hesitated response when hitting the throttle, and then bam! SEL flashing for about a minute. Then it goes out and stays out. If you pull the codes I will see a P0300 code "pending", which means it saw a misfire but as long as it doesn't happen again within so many miles or warm-ups it will not set a solid SEL. But yesterday I did a few stop and drives and had it occur 3 times within about 15 miles. When it happened the 2nd time it flashed for a minute then went solid. Now when I pulled the code it shows confirmed and permanent for P0300. Looking through the data on misfires, I do see a few dozen misfires on cylinder 1 and maybe a dozen on #6. The good news is with the light on constant now I can run the truck today over to the dealer and it will be another documented occurrence of it happening. They won't be able to just say come back when the light is solid. 

 

So I couple more things I've noted. I've read driving in L disables the DFM which I really do belueve is what causes this misfire BS. I drove the truck in L9 for weeks with no issue. The truck runs better like that as well. Something that people may have noticed, when in drive when you come to a stop the truck will feel like it's going to stall and have a slight shake when stopping at very low speeds. With L9, the truck doesn't feel like that. I believe the DFM is shutting down cylinders when coming to a stop and that's the shake or shimmer that I feel. I also feel a slight shake when the truck is in Drive and running at 50-60mph. Again, in L9 I don't feel that. 

 

I do like driving the truck in L9 but I need to keep driving it in Drive and trying to cause the SEL light as much as possible. For one I want the truck diagnosed and fixed. Secondly, if they don't do something about it soon I'm probably already qualified for lemon law. After this visit today I'm calling GM and starting that process. Something has to give, I love everything about my truck except for these lifter/dfm and engine issues that seem to be plaguing 21 trucks. 

[kmeleon]

Here's some screenshots of the 2nd scan yesterday with the snapshot data of what was occurring in the ECM when the truck misfired. Maybe someone will notice something I didn't. 

[newdude]

I see you mentioned L9, so I assume you are 5.3 with a 10 speed.

 

Is the light coming on but there is no actual misfire, so a "phantom" P0300?

 

IF so, did the dealer perform 21-NA-154?

Quote

 

21-NA-154: DTC P0300 Engine Misfire Detected without Drivability Concern or Misfire Felt - (Jul 5, 2021)

Subject: DTC P0300 Engine Misfire Detected without Drivability Concern or Misfire Felt

Involved Region or Country

United States, Canada, Mexico, Middle East, Chile, Paraguay, Uruguay, Thailand.

 

Additional Options (RPOs)

Note: Does not include RPO (YK9) for model year 2021

 

Condition

Some customers may comment that the SES (Service Engine Soon) lamp is illuminated or was Illuminated and turned off. Customers may also comment on a check engine light was flashing while driving up a long grade or smooth road with steady throttle. Also, with this particular condition the customer will not feel any misfire or have a drivability concern.

 

Technician may notice DTC P0300 (Engine Misfire Detected) active or stored in history.

 

Cause

The cause of the condition may be the P0300 diagnostic falsely setting the DTC under certain driving conditions.

Upon reviewing GDS data technician may notice misfires being recorded on any cylinder but may be more noticeable on cylinders 1 and 6.

 

Correction

If you encounter a vehicle with the above DTC DO NOT replace any parts. Engineering has released an updated calibration to address this concern.

 

Reprogram the ECM (Engine Control Module) with the latest calibration and perform the “Crankshaft Position Variation Learn” procedure. Once updated calibration is installed operate vehicle and verify DTC does not return.

Important: Once ECM calibration has been updated it will be necessary to perform the “Crankshaft Position Variation Learn” procedure in service information. If this procedure is not done the ECM calibration will not provide the desired results.

 

Important: This calibration will not address any true engine misfire. If a true engine misfire exists refer to service information for further information and diagnosis.

 

 

 

 

If they did and its STILL doing it, GM engineering is still looking into this issues on 10 speed 5.3 trucks.

 

 

Quote

 

#PIP5816: P0300 Setting After Bulletin 21-NA-154 Was Performed - (Jul 30, 2021)

Subject: P0300 Setting After Bulletin 21-NA-154 Was Performed

Involved Region or Country

United States, Canada, Mexico, Middle East, Chile, Paraguay, Uruguay, Thailand.

Condition

A customer vehicle may have a concern of a P0300 setting after bulletin 21-NA-154 has been performed 

Cause

Unknown Engineering is looking into this concern

Correction

Make sure the Crankshaft Position Variation learn was performed, refer to Crankshaft Position Variation Learn in SI.

Important: If this procedure is not done then the ECM calibration will not provide the desired results.

Note: This is only for vehicle listed above with 5.3L L84 and 10-speed MQB

If the above has been done, be advised that engineering is looking it to the concern. 

If the misfire is felt please follow SI for the concern. 

 

 

[jeepincbum11]

Does it do it when you press the auto shut off disable button as soon as you start the truck?

 

[Whiskeyranch]

Mine did the same with the same code. Broken valve spring 6.2 with the 10 speed. They only wanted to replace the one spring. I said I didn’t want the truck back until they were all replaced. My truck wasn’t in the window of the recall but the engine was. Built at an earlier date. A few weeks later they replaced all the springs and everything’s been fine since. Problem showed up at 197 miles. Now have 8,000 but yours sounds like a transmission issue? Sorry you’re having problems. Very strange. I hope you get it figured out.

Edited August 11, 2021 by Whiskeyranch
More info

[kmeleon]

1 hour ago, newdude said:

I see you mentioned L9, so I assume you are 5.3 with a 10 speed.

 

Is the light coming on but there is no actual misfire, so a "phantom" P0300?

 

IF so, did the dealer perform 21-NA-154?

 

 

 

If they did and its STILL doing it, GM engineering is still looking into this issues on 10 speed 5.3 trucks.

 

 

 

Yes I have the 10 speed. They HAVE NOT done that update yet. My plan is to demand they do it today. This has gone on for too long. Thanks for the advice. Interesting, didn't know there may be a 10spd issue. Thanks for that. 

[kmeleon]

1 hour ago, jeepincbum11 said:

Does it do it when you press the auto shut off disable button as soon as you start the truck?

 

I can't answer that, I usually don't push that button before it shuts off at the first stop light. Then it gets pushed

[kmeleon]

34 minutes ago, Whiskeyranch said:

Mine did the same with the same code. Broken valve spring 6.2 with the 10 speed. They only wanted to replace the one spring. I said I didn’t want the truck back until they were all replaced. My truck wasn’t in the window of the recall but the engine was. Built at an earlier date. A few weeks later they replaced all the springs and everything’s been fine since. Problem showed up at 197 miles. Now have 8,000 but yours sounds like a transmission issue? Sorry you’re having problems. Very strange. I hope you get it figured out.

Yes, I'm aware of potential valve spring issues too, my truck falls into that time line as well. Valve springs, lifters, possible 10 spd issue that new dude eluded to.... Good lord

Edited August 11, 2021 by kmeleon

[newdude]

29 minutes ago, kmeleon said:

Yes I have the 10 speed. They HAVE NOT done that update yet. My plan is to demand they do it today. This has gone on for too long. Thanks for the advice. Interesting, didn't know there may be a 10spd issue. Thanks for that. 

 

 

I would bring up that 21-NA-154 and have them try the reprogram step by step.  Just be aware that its a 50/50 chance it might come back again because of that follow up PI and GM's investigation on why the reprogram may or may not fix a 10 speed truck.  

[kmeleon]

9 minutes ago, newdude said:

 

 

I would bring up that 21-NA-154 and have them try the reprogram step by step.  Just be aware that its a 50/50 chance it might come back again because of that follow up PI and GM's investigation on why the reprogram may or may not fix a 10 speed truck.  

I will bring it up today, thank you for the help and info. 

[kmeleon]

3 hours ago, Whiskeyranch said:

Mine did the same with the same code. Broken valve spring 6.2 with the 10 speed. They only wanted to replace the one spring. I said I didn’t want the truck back until they were all replaced. My truck wasn’t in the window of the recall but the engine was. Built at an earlier date. A few weeks later they replaced all the springs and everything’s been fine since. Problem showed up at 197 miles. Now have 8,000 but yours sounds like a transmission issue? Sorry you’re having problems. Very strange. I hope you get it figured out.

Whiskey, did you notice any driveability issues? How often was yours throwing the code? 

[Whiskeyranch]

When it happened it started shaking then died on the off ramp of the freeway. I got it started again then pulled over immediately hoping to not do any further damage. I then waited over a few hours for the dealer to have it towed, Christmas Eve, 24° out. Good times. 

[kmeleon]

1 hour ago, Whiskeyranch said:

When it happened it started shaking then died on the off ramp of the freeway. I got it started again then pulled over immediately hoping to not do any further damage. I then waited over a few hours for the dealer to have it towed, Christmas Eve, 24° out. Good times. 

Ouch, terrible way to start out with a new truck ! I bought mine Monday of Xmas week. Great ride home, then the ****** how started in February. 

 

Anyway, went to the dealer after work. Advisor tells me they've had a few trucks in for this same issue, they've run that ecm update and it hasn't fixed it. Ran the codes... P0300 (duh) and that gm doesn't have a fix for it. So I'm calling gm tonight to try for one of two things: a 100k mile warranty on anything engine related on them or a buyback of rhe truck since I've been dealing with this for 6 months, multiple times at the dealer and they don't have an answer on how to fix it. We shall see. 

[kmeleon]

Bringing this back to the top. Heard back from the investigator yesterday. Basically she has nothing to tell me yet, she spoke to the dealership and they claim that I'm bringing my truck back in for service but that's not true I don't have an appointment currently and no one has reached out to me. She does say GM is working on the issue if indeed my problem is the same as what they believe it to be and that she doesn't have an update on that or when that fix will be released. My response to her was how long am I supposed to drive this truck that flashes the SEL light every couple of days? I started mentioning lemon law with her and that may get me somewhere she's looking into an extended warranty on my truck to keep me happy. I'm not sure that's going to happen though. I told her I would reach out to the general manager at the dealership and put a good faith effort in with him but if nothing else comes from this I'm going to demand to buyback and ask for a new GMC or possibly go buy a Tundra. 

 

I'm getting even better at setting the service engine light off. I can almost do it at will each day. So that will be helpful in eventually showing somebody the issue.

 

This sucks, I love my truck but I don't know how long I'll continue this game with them. I may go test drive a tundra this weekend.

[Rhino83]

Talking about ECM updates and the 10 speeds...I too have had the CEL but no performance issues that I can tell.  However, I have taken my truck in four times now but the first two were computer hookups and the last two were service appointments that are related to this very issue.  The first service appointment, they updated the software in the ECM.  Drove it for about a week and a half and CEL came back on.  After two days, light went off and I got an appointment about a week later.  This time they discussed replacing the ECM since the ECM already had the updated software.  Was told when I picked it up that the ECM software was not designed for the 5.3s with 10 speeds and that GM was working on an updated software.  Tech even showed me the bulletin.  Just some food for thought I guess.