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First time Chevy owner..first post- My 2021 Silverado Trailboss LT has a check engilne light that comes on about evey 300 miles.  It is a generic p300 code.  Onstar tells me to bring it in, chevy service/dealer says it looks fine, and the code is generic so they can't fix anything.  The 3rd time they said they would contact GM for a more thourough inspection- the GM tech says they are aware of the issue, and released a service bulliten on 7/30 about the code.  No solution as of yet, so they advised- just drive it, ignore the check engine, and they will contact me when they have a solution.  Is this how Chevy typically works?  I have never heard of ..hey we know something is wrong, but we cant fix it, so just keep driving.  Has anybody else had this code issue resolved?

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Unless you are also experiencing drivability issues then I would say give them time. It could be completely a software glitch and nothing actually wrong with the truck. a P300 is a symptom code for when the computer detects 2 or more cylinders misfiring. Without more specific codes for exactly which cylinders or for some other sensor the mechanics would just be spinning their wheels guessing at what the cause might be.

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44 minutes ago, Sarah Ivankovich said:

First time Chevy owner. First post- My 2021 Silverado Trailboss LT has a check engine light that comes on about every 300 miles.  It is a generic p300 code.  Onstar tells me to bring it in, Chevy service/dealer says it looks fine, and the code is generic so they can't fix anything.  The 3rd time they said they would contact GM for a more thorough inspection- the GM tech says they are aware of the issue, and released a service bulletin on 7/30 about the code.  No solution as of yet, so they advised- just drive it, ignore the check engine, and they will contact me when they have a solution.  Is this how Chevy typically works?  I have never heard of ..hey we know something is wrong, but we cant fix it, so just keep driving.  Has anybody else had this code issue resolved?

Welcome to the site.

 

If you do not like the answer they keep giving you, take it to another Chevy dealer and see what they say.

It is your truck, you have no obligation to keep going back where you bought if you feel that you are not being treated appropriately.

And, make sure that all of this is being documented, in case you do have a failure, there will be records.

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5 hours ago, Sarah Ivankovich said:

First time Chevy owner..first post- My 2021 Silverado Trailboss LT has a check engilne light that comes on about evey 300 miles.  It is a generic p300 code.  Onstar tells me to bring it in, chevy service/dealer says it looks fine, and the code is generic so they can't fix anything.  The 3rd time they said they would contact GM for a more thourough inspection- the GM tech says they are aware of the issue, and released a service bulliten on 7/30 about the code.  No solution as of yet, so they advised- just drive it, ignore the check engine, and they will contact me when they have a solution.  Is this how Chevy typically works?  I have never heard of ..hey we know something is wrong, but we cant fix it, so just keep driving.  Has anybody else had this code issue resolved?

See my thread here. Same issue, been going on since february/March. Can you tell me how you're driving it when the light goes off? How fast? Pulling away from a stop? Driving steady down the road? Etc? 

 

Mine occurs pulling away from a rolling stop while turning. 

 

 

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Also, I bet if you have a code reader you'll see misfires on cylinder 1 and possibly another one (mine shows on 6 too). But it only throws P0300 which is a generic misfire code. If you look through the cylinder data you'll see misfires I bet. 

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This was published over the summer.  Seems there is a calibration update?

 

https://gm-techlink.com/?p=15026

 

Engine Misfire Detected without Drivability Concerns

July 16, 2021

An engine misfire DTC may be set on some 2020-2021 Silverado 1500 and Sierra 1500 models equipped with the 5.3L V8 engine (RPO L84). However, the misfire may not be noticed by the driver or the vehicle may not have any drivability concerns. The Check Engine MIL may be illuminated (Fig. 😎 or may have been flashing while driving up a long grade or a smooth road with steady throttle input. DTC P0300 (Engine Misfire Detected) may be set as active or history in the Engine Control Module (ECM).

 

F08-check-engine-2.pngFig. 8

 

The detected misfire condition may be the result of the P0300 diagnostic falsely setting the DTC under certain driving conditions. GDS2 data may show misfires being recorded on any cylinder, but they may be more noticeable on cylinders 1 and 6.

To address the detected misfire condition, an updated calibration has been released. Reprogram the ECM with the latest calibration and perform the Crankshaft Position Variation Learn procedure. Do not replace any parts for the condition.

TIP: To avoid warranty transaction rejections, the warranty claim code provided on the SPS Warranty Claim Code (WCC) screen must be recorded on the job card (repair order).

The updated calibration does not address any true engine misfire. It only updates the P0300 diagnostic in the ECM. If the engine is actually misfiring, refer to the appropriate Service Information for additional diagnostic information.

Once the calibration has been updated, drive the vehicle and verify the DTC does not set.

 

Crankshaft Position Variation Learn Procedure

The Crankshaft Position Variation Learn procedure must be performed or the updated calibration will not provide the desired results.

The crankshaft position sensor variation or reluctor ring learn is used to calculate reference period errors caused by slight tolerance variations in the crankshaft and the crankshaft position sensor. The calculated error allows the ECM to accurately compensate for reference period variations, which enhances the ability of the ECM to detect misfire events over a wider range of engine speed and load. The compensation values are stored in ECM memory after a learn procedure has been performed.

For additional information, refer to Bulletin #21-NA-154.

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8 hours ago, 1997SierraSLT said:

Welcome to the life of GM ownership.  With as many times as you’ll be seeing that CEL, GM should just be giving you a scan tool with every vehicle purchase.

 

In my '09 Tahoe w/ 5.3 I saw the money light exactly once... at 180k when the evap vent valve bit the dust.

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On 8/31/2021 at 10:41 AM, Sarah Ivankovich said:

First time Chevy owner..first post- My 2021 Silverado Trailboss LT has a check engilne light that comes on about evey 300 miles.  It is a generic p300 code.  Onstar tells me to bring it in, chevy service/dealer says it looks fine, and the code is generic so they can't fix anything.  The 3rd time they said they would contact GM for a more thourough inspection- the GM tech says they are aware of the issue, and released a service bulliten on 7/30 about the code.  No solution as of yet, so they advised- just drive it, ignore the check engine, and they will contact me when they have a solution.  Is this how Chevy typically works?  I have never heard of ..hey we know something is wrong, but we cant fix it, so just keep driving.  Has anybody else had this code issue resolved?

Looks like I found the right site! I purchased a new 2021 Trail Boss 5.3 in March. With in the first 600 miles check engine light came on, dealership said it was bad injectors 1 and 6, which they replaced. Four months later same thing happened, this time they brought in a GM Tech adviser and "reprogramed" the truck. This was after having it for a month. I just got it back and after a month same issue. I took it in and after having it for a week waiting on GM I was called today and told to pick it up tomorrow. The check engine light will be on but its ok to drive until we get another update! So GM wants me to knowingly drive a vehicle that is not working properly. I am in the middle of a buy back and have been denied by GM. I can't tell you how disappointing it is to deal with a manufacture that will not stand behind their product.

 

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9 hours ago, Dweston said:

Looks like I found the right site! I purchased a new 2021 Trail Boss 5.3 in March. With in the first 600 miles check engine light came on, dealership said it was bad injectors 1 and 6, which they replaced. Four months later same thing happened, this time they brought in a GM Tech adviser and "reprogramed" the truck. This was after having it for a month. I just got it back and after a month same issue. I took it in and after having it for a week waiting on GM I was called today and told to pick it up tomorrow. The check engine light will be on but its ok to drive until we get another update! So GM wants me to knowingly drive a vehicle that is not working properly. I am in the middle of a buy back and have been denied by GM. I can't tell you how disappointing it is to deal with a manufacture that will not stand behind their product.

 

Can you explain when your SEL light starts blinking? How fast, pulling away from a stop? Steady speed? Light acceleration? 

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After Start up 1/4 of mile from home. Started blinking for 1/2 mile then stayed solid. Took it to the dealer now waiting for a calibration upgrade for the 10 speed trans. They cleared the code, light is off and no idea when GM will find the fix. 

 

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This is exactly how mine get set off as well. Usually within a quarter mile of my house or wherever I'm leaving. Usually pulling away from a stop sign and less than 20 miles an hour. Mine has went off 30 some times in 7 months. 

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5 hours ago, Dweston said:

After Start up 1/4 of mile from home. Started blinking for 1/2 mile then stayed solid. Took it to the dealer now waiting for a calibration upgrade for the 10 speed trans. They cleared the code, light is off and no idea when GM will find the fix. 

 

How do you know it's the transmission causing the issue? Did the dealer tell you that?

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22 hours ago, kmeleon said:

How do you know it's the transmission causing the issue? Did the dealer tell you that?

According to the dealer and the GM tech, there also is a bulletin about this #PIP5816 

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