2021 GMC Sierra 1500 complaints

Loss of power, had engine repaired, replaced passenger side head and cylinder. Now drivers side is having the same issue.

Cam Shaft and Lifter failure. Lifters were replaced 3 times

My vehicle is on a recall list. Took it to the dealership for engine vibration test. They changed oil and put on a new cap. My engine blew up a couple weeks later. They replaced my motor. It blew up on the mechanics test drive. I'm now waiting on my 3rd motor. They have had it for over 5 months now.

2021 GMC Sierra 1500 equipped with 6.2L L87 engine. At approximately 97,000 miles, the engine developed a significant knocking noise. I immediately took the vehicle to an authorized GMC dealership for diagnosis. The dealer determined that the engine required replacement but advised that my VIN was not included in GM Recall 25V-274. The dealer quoted approximately $15,000 for replacement. I subsequently had an independent repair facility replace the failed engine with a genuine GM replacement engine at a cost of approximately $12,400. I am reporting this because the failure appears similar to the L87 engine bearing/crankshaft failures addressed by Recall 25V-274, despite my VIN not being included in that recall.

I had the L87 recall completed, and the vehicle passed inspection. The dealership completed the required protocol and replaced the engine oil with 0W-40. Approximately 6,000 miles later, while traveling at about 75 mph and six hours from home, I experienced a brief loss of power followed by an immediate return of power. My wife and I noticed it but, with no warning lights or alerts, continued driving while monitoring the vehicle. About 10 miles later, we began hearing a faint squealing noise that progressively became worse. I was able to exit the highway safely, but once I came to a complete stop, the engine shut off and would not restart. I had the vehicle towed to the nearest dealership, where it was determined that I had suffered a catastrophic engine failure. No loaner vehicle was available, leaving my family stranded six hours from home with an inoperable vehicle. It took approximately seven to eight weeks for the repair to be completed. When I received the vehicle back, I immediately noticed something still was not right. At around 40 mph and 1,000 RPM, the truck would shudder or hesitate. My local dealership diagnosed a poor spark plug connection on cylinder #3, which was causing arcing and a misfire. After the connection was repaired, the issue was resolved. My local dealership is currently working with the repairing dealership to address several minor workmanship issues, including wire clips, fittings, and missing bolts. This entire event was unexpected. There were n

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at 60 MPH, the vehicle began to shake uncontrollably. A knocking sound was heard from the engine, and the vehicle entered limp mode. No warning lights illuminated. The contact was able to coast the vehicle to the residence. The vehicle was later towed to the dealer, where it was diagnosed that the engine failed and needed to be replaced. The contact associated the failure with NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling). The vehicle was not repaired. The manufacturer was notified of the failure and informed the contact that the VIN was not included in the recall, and the contact was advised to file a complaint with the NHTSA Hotline. The failure mileage was 81,000.

Rear wheel lock up. Very unsafe. I am on my 3rd valve body for my transmission. GM doesn’t want to replace transmission but will warranty for 150k miles. I bumped a semi during one of my lock ups.

Driving on the highway lost proportion/acceleration, loud knocking coming from the engine

The contact owns a 2021 GMC Sierra 1500. The contact stated that the vehicle was experiencing excessive oil consumption. The low oil level was observed, and the oil warning light illuminated. The vehicle was previously serviced at the dealer, where it was discovered that the oil was 3 quarts low at approximately 56,653 miles. The vehicle was returned to the dealer, where an oil consumption test was performed. After driving 3,000 miles, it was observed that the oil level was 2 quarts low on July 16, 2024. The dealer confirmed there was no recall coverage, and the vehicle was not repaired. The contact associated the failure with NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the dealer and manufacturer confirmed the VIN was not included. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 59,075.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 25 MPH near the residence with the contact's daughter as a passenger, the vehicle experienced a complete loss of motive power when depressing the accelerator pedal. Several unspecified warning lights illuminated. The contact and the passenger pushed the vehicle to the residence. The vehicle was towed to an independent mechanic, where it was diagnosed that the electrical system experienced a severe power loss and the electrical modules were damaged. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 89,000.

While driving down an isolated 2 lane road in West Texas, the engine in my 2021 GMC Sierra 1500 began making knocking sounds and vibrating badly. The truck's acceleration was extremely sluggish and the vibration worsened at slow speeds. I was able to slowly make my way back towards a dealership, where the diagnostic teardown revealed a bent pushrod and camshaft damage.

For close to one year, there feels like a catch, grind, stall, or slight shake, mostly while the vehicle is shifting gears, made worse or noticed more by higher speeds like driving on the highway vs. slow city streets. It's difficult to explain or assess so not sure if it is the engine or transmission. With the open recall from GMC on some vehicles with the same engine as mine it is concerning that maybe it should have been included.

1. What component or system failed or malfunctioned, and is it available for inspection upon request? The engine oil consumption system/engine is experiencing excessive oil consumption. My 2021 GMC Sierra is equipped with the 6.2L engine, and the engine is consuming oil at a rate that I believe is abnormally high. The vehicle and engine are available for inspection upon request. I am also concerned that my vehicle may be affected by an engine-related recall or safety campaign associated with this engine. When attempting to verify the recall status, the system appears to have an error and is not identifying my vehicle. I am requesting that the vehicle’s VIN and engine configuration be manually verified against all applicable recalls and safety campaigns. 2. How was your safety or the safety of others put at risk? The excessive oil consumption creates a potential safety concern because I am concerned that the engine could become critically low on oil while I am driving, potentially resulting in engine damage, loss of power, or complete engine failure. This could occur while traveling at highway speeds or in an area where it may be difficult or unsafe to stop. I regularly travel with my family, which increases my concern about the possibility of an unexpected engine failure and the potential risk to my passengers and other motorists. 3. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. I previously addressed this issue with Newton Chevr

While driving my son to school we were driving 45 mph and the entire engine shut off and lost all power. Engine would not restart. Took it to the dealer and was told the engine was dead.

I purchased this truck from a used car dealer. It had received the fix in January this year. They sold it to me I put 15,000.00 down and financed 15,000.00. I had the truck two weeks and was driving down the road to pick up some tools from a friends. I pulled from a drive way I heard a pop likei hit something In The road nothing was in the drive or road I could have hit. I made it two stop signs to make the turn too go pick up the tools and as I am slowing down to stop the stuck shuts off at like 45 miles an hour and leaves me comming to a stop with a truck crank crank crank no start. Cause it said shift I to neutral to restart. I did and the engine went to cranking over and o er really fast. And I was Abel to get control and get stopped at stop sign blocking the stop sign and a guy with a boat behind me. My friend came with his truck and pulled me from intersection up into His yard. And I had car lot I bought it from come get it they tried to finance me a motor thru there prefers dealer. I went to them they explained that the cams and timing chain was staying still as they turned the engine Over by hand. The timing chain stayed staionary. I researched the truck online figured out there is a l87 recall and had it taken to dealer they are offering good will payment on labor because it is 6, 000 miles past the 150000 dead line Wich I only placed just over a thousand of the 156000 miles on this truck. I have been without this truck for 31 days as of today. And I feel they should

Rear sliding window has plastic body seam that is broken allowing water to leak into the truck and cause mold and rust

2021 6.2L GMC Sierra Denali. Has the L87 engine that is recalled but yet my truck doesn’t fall under the recall although the recall is for 2021-2024 engines. Everything that the engine recall states is the issue with my truck, I have service report from dealership stating that there is wear/breakage of cam shaft/crank shaft amongst other things including cylinder 3 and 5 misfiring , bearings broken , filings in the oil , banging in the engine and safety lights on. My local GMC dealership recommended that the only acceptable action was to replace the engine at my cost of course. This is unacceptable of a supposed reputable large corporation not caring about the “little guy”. The truck only has 136000 kms on it and I was only going 60 km/hr when this happened. Please help as I feel GM knows this engine is faulty but somehow has managed to escape a recall on my vin number

Push on accelerator truck barely would go, shifted hard, codes check engine lights flashing, engine sounded bad

Transmission Valve Body failure. - Caused wheels to lockup momentarily and killed the engine with sudden loss of propulsion. Link to video of incident: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

A small drip started approximately 18 months ago from top middle of left side window in rear slider. It was first mistaken as blow by from car wash. Leaking slowly progressed to dripping down middle of both side windows in rear sliders. Leaking progressed to drops coming from under headliner then dropping on side portions of rear slider. It then would drip onto seat or behind seats. Leakage was consistent with TSB 18-NA-383 as well as 20-NA-142 and 24-NA-103. In discussing with dealership, they recommended likely microfractures and sealant process called for in bulletins would likely resolve matter. As due diligence, spoke with independent glass shop to confirm. Glass shop indicated would not know until physically checked cracks/source of leak and looked for damage but based upon photos it appeared to be several frame fractures consistent with bulletins. I arranged rear slider replacement through independent shop. Upon pulling OEM slider, numerous stress cracks and fractures were noted. These included stain marks from water intrusion. Photos included showing original leaking as well as sample of cracks in original OEM plastic frame portion.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission was shuddering, especially while driving uphill. The dealer was contacted, and the vehicle was diagnosed and determined to have a failure associated with a GM TSB for the incorrect transmission fluid inside the transmission reservoir. The vehicle was not yet repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 38,875.

P1010 and P2B86 engine code, constant cooling fan on engine. Confirmed by dealership, quoted for coolant control valve. VIN not included in special coverage N252508341 for this known issue. Limited engine power alert, unable to maintain speed on highway. Dangerous condition traveling under speed limit.

Engine temp rises way above mid-level and will stay there for several minutes before cooling back down to normal temps. 2 different mechanic shops have told me it's the coolant control valve, but want $2500 to fix it. This service bulletin is for the same year, make, model, and motor as my truck, but the dealership said it wasn't covered.

2021 Harley Davidson Sierra 4WD, 6.2L L87. Started the truck in the morning and immediately heard intermittent, very loud banging noise coming from engine. Shut truck down quickly and had it towed to dealer. Diagnosis was bent pushrods & failed lifters which were replaced under warranty. Factory warranty expired only 4 months after this failure, and the recall does not include my VIN so I did not get an extended warranty or any other protection. GM has yet to even reimburse the tow bill. Completely unacceptable for a truck that was well over $100k when new.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 70 MPH, the vehicle suddenly lost motive power, decelerated, and failed to properly accelerate while depressing the accelerator pedal. The check engine warning light was illuminated. After exiting the freeway, the vehicle stalled. The vehicle was towed to the residence and then later towed to the dealer for assistance. The contact was informed that there were metal shavings inside the engine oil. The contact was informed that the engine needed to be replaced. The vehicle was not yet repaired. The contact was informed that the VIN was not included in NHTSA Campaign Number: 25V274000 (ENGINE AND ENGINE COOLING). The contact stated that the vehicle had experienced the failure listed in the recall. The manufacturer was not yet contacted. The failure mileage was 149,000.

CORRODED GROUNDING STRAP FAILED CYLINDER 5 GLOW PLUG CIRCUIT CRACKED AND SEPARATED EXHAUST BACKPRESSURE VALVE

The vehicle has about 38000. The warrantee expired about 6 months ago. About three weeks ago I started the engine, it sounded like a cement mixer filled with rocks. I had it taken to my dealer. They investigated the problem and determined that it has bad lifters and bent push rods. The dealer told me that it is a known problem but it is not covered by the current 6.2l engine recall

Vehicle: 2021 GMC Sierra SLT | VIN: [XXX] Dealership: Carl Black GMC Roswell, GA (11225 Alpharetta Hwy, 30076) | Invoice #[XXX] | Service Date: [XXX] Paragraph 1 – Suspension Hazard: Dealership diagnosed a worn left upper ball joint (popping sound on left turns) and installed Rough Country aftermarket upper control arms on my stock-height Sierra SLT. These arms are designed for lifted suspension and alter factory caster/camber geometry, placing extreme stress on ball joints. This can cause sudden ball joint separation, wheel collapse, and total loss of steering control at speed. The dealership admitted on the invoice they "could not find branding" on original parts and chose non-OEM lift components without my consent or any safety disclosure. Paragraph 2 – Brake Failure & No Safety Warning: The same service included a full front/rear brake job (pads + resurfaced rotors) using their certified technicians and parts. After pickup, the brakes failed to operate properly. When I returned, the service manager refused to correct their own workmanship and instead quoted $1,900 to repair the very brakes they just serviced. Most critically, at vehicle pickup they issued no written or verbal safety warning—no "do not drive" instruction—despite the brakes being knowingly compromised, endangering me and the public. Paragraph 3 – Requested Action: The service manager was unprofessional, condescending, and refused accountability. I request an immediate NHTSA investigation into Carl Black GMC

On June 25, 2026, at approximately 84,000 miles, while traveling approximately 60-65 mph on Highway 121 in a posted 65 mph zone, driving my 2021 GMC Sierra 1500 AT4 equipped with the 6.2L L87 engine, multiple warning messages suddenly appeared, including “Check ESC,” “Check Parking Brake,” “Check Brakes,” and “Check Engine.” The engine began operating abnormally. I drove directly to Sewell GMC because I was concerned that the engine could fail or the vehicle could lose propulsion while in traffic. There was no crash, fire, or injury. Sewell GMC inspected the vehicle and confirmed catastrophic internal engine damage. The technician found metal debris in the engine oil and oil pan, damaged internal bearings, and camshaft/lifter damage. Sewell advised that the complete engine must be replaced. The vehicle remains at the dealership, has not yet been repaired, and the engine and failed components should be available for inspection. Before this incident, I had not experienced warning lights or symptoms indicating that an imminent catastrophic engine failure would occur. GM and the dealership advised that my VIN is not included in the current L87 engine recall because the engine was built in 2020. However, the diagnosed bearing damage, metal contamination, and catastrophic engine failure appear similar to the engine failures addressed by that recall. I am reporting this because an unexpected internal engine failure while driving creates a serious risk of loss of propulsion and a col

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 35 MPH, the engine was making an abnormal sound, and the vehicle failed to accelerate. The engine was popping and making cranking sounds, with several unknown warning lights illuminated. The vehicle was driven back to the residence with the issues. The contact referenced NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); as a possible cause for the failure; however, the VIN was not included in the recall. The vehicle was taken to a dealer where it was determined that there was metal fragments found in the oil filter, and recommended that the engine be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 50,000.

I'm not sure if they've pulled it out yet. They said two weeks to get motor. Engine started shaking and then started knocking. Had wrecker take it to GMC dealer they said it needs an engine. It is a 2021 6.2 carbon pro 1500 Sierra AT4 it did not come up on recall list and I don't know why? it obviously the same problem.

At 115,000 the coolant control valve has gone out. GM acknowledges this issues in 2020 model trucks. My truck is a 21 and displaying the same characteristics. A simple google search will show this is a known issue in 2021 vehicles as well. In 2020 model trucks GM has provided a special 150,000 mile warranty to replace this part. GM needs to step up and provide a proper warranty/recall for the affected 2021 models.

P1098 code indicating stuck/ unresponsive engine coolant control valve. N252508341 exists for this part; however claim is my VIN is not covered under the bulletin or included on any standard warranty coverage. Part should last more than 150k miles, vehicle less than 90k. Less than 2 weeks ago suffered a complete EBPV failure that destroyed coolant and DEF lines, also not covered. No explanation for why my specific VIN (a 3.0L diesel in the supposedly covered MY) is excluded. Have been unable to find evidence of any applicable vehicles that were 'covered' under this bulletin. Fault forces an unexpected derate which can engage while accelerating, including while merging into freeway traffic. This is an obvious safety hazard. Engine check light illuminates approximately 30 to 60 seconds before derate limits top speed and throttle response. No messages to operator. Dealer has confirmed issue.

The 10 speed automatic transmission shakes and jumps between gears. The transmission also shakes and rumbles at cruising speeds. The diesel engine version of this truck is already recalled. My truck is a gas engine and should also be recalled. This is the same defective 10 speed transmission used in all GM vehicles and recalled in many. This vehicle needs to be recalled and fix before the wheels lock up and kill someone.

I was driving and my check engine light came on a mile from my house. I drove home and the next morning, I started my truck. It was loud and pulsating like it wanted to stall out. I had it towed to a repair shop. They plugged into the truck and said it was giving code P0016. I had it towed to another place and that it is where it is sitting now. I also received a email from onstar saying "A critical issue with the engine and transmission system in your 2021 GMC sierra Crew Cab has been detected. P0016 was detected. I searched my VIN # and it says that there are no recalls on my truck. I do see that there was a silent recall on the engine that is in my truck.

I am submitting supplemental evidence regarding my 2021 GMC Sierra (VIN [XXX]) for Recall Query RQ26001, Campaign 25V-274. Despite multiple repair attempts, my vehicle remains unsafe and non-compliant with GM Service Bulletin N252494002. The recall remedy was performed deficiently. [XXX] Northeast Buick GMC installed a remanufactured short block instead of the required complete engine, reused the original seized-engine oil pan (which continues to leak), and failed to address critical electrical damage. Documentation proves they deleted Labor Operation 14BUZ (Engine Electrical) after their technician noted a blown mega fuse. A second dealer, Penske Chevrolet, subsequently deleted Labor Operation 77CVZ01 from my repair order, demonstrating a systemic pattern of ignoring recall-required repairs. Electrical damage has cascaded, resulting in a burnt fuse block and active faults P0615, P0617, P26E4, P26E6, U0623, and U0284. More critically, within 24 miles of my last service, the vehicle developed a new, severe safety failure: the "Service Brake Pad Monitor" system failed, accompanied by a red "Service System" dashboard alert and a noticeably spongy brake pedal. These brakes were recently serviced, yet this failure introduces a new risk of crash not present prior to the recall "remedy." GM Executive Resolution Case XXX has provided no resolution, reimbursement, or safety assurance, ignoring all deadlines since XXX. I possess extensive documentation, including service orders showing

Transmission shuddering, harsh or delayed shifting, and erratic gear changes. The truck jerks really bad during each shift of the ten speeds. A vibration or shudder typically occurring at speeds between 25-65 mph under light throttle. Also makes a bad noise every times it’s shifting. I have no lights on the dash and the gmc app tells me everything is fine when clearly it’s not . I see there’s a recall for my year and make but for some reason my vin doesn’t fall in the category

My car suffered a catastrophic engine failure, metal schards were found in the oil filter and was left out of the 2021 recall 25V274. The in service date of vehicle is March 13, 2021. The car was 83 days out of warranty when the engine failed. The truck has 47,000 miles on it. They are now trying to charge us, barter with us. They have gone from $2800 for repair, negotiated down to $100 to sign this off as a good will repair stripping us of lemon law rights and future recall remedies. Car is currently sitting at the dealership.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while turning the ignition on, the "Service Parking Brake" message was displayed, and the check engine warning light illuminated. Additionally, the engine ran rough. The vehicle was taken to the dealer, where it was diagnosed that the engine lifters needed to be replaced; however, the dealer could not diagnose if there was further engine damage until the lifter repair was completed. The manufacturer was made aware of the failure. The failure mileage was approximately 72,530.

I own a 2021 GMC Sierra AT4 3.0L Duramax (VIN [XXX]). The vehicle has codes P1098 (Coolant Control Valve Performance) and P129F which coincides with the first code. My dealer believes this is consistent with an Engine Coolant Control Valve failure. I understand Special Coverage XXX exists for this issue, but I've been told my VIN is not included. My truck has the exact engine, symptoms, and diagnostic codes addressed by Special Coverage N252508341, but my VIN is excluded. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the "Add oil to engine" message was displayed. The vehicle was driven to an AutoZone within two minutes and turned off. Upon inspection of the engine oil level, the contact observed that the dipstick was completely dry. The dealer was notified of the issue, and an appointment was scheduled for an oil consumption test. The vehicle was not yet diagnosed or repaired. The contact stated that the vehicle had been serviced for a routine oil change on April 21, 2026, at 53,590 miles. The contact related the failure to NHTSA Action Number: RQ26001(ENGINE). The manufacturer was not made aware of the failure. The failure mileage was approximately 56,802.

Since purchase of my 1500 Sierra 6.2L on 10FEB2021, the vehicle has always appeared to burn an excessive amount of oil which is consistent with GM’s 6.2L engines and has created safety issues leading to sweeping recalls on this engine model from 2021-2024. I have been informed that the engine was consistently down 2+ qts of oil at every recommended oil change (approximately every 5000mi) although GM literature indicated that this level of consumption was usual in their 6.2L engine. In a JAN26 oil change at approximately 35,000mi I was told that my engine was down over 3qts of oil. On 17FEB2026 I took my vehicle into my Chevy/GMC Dealership to request an oil consumption test at ~35, 089mi. On 30JUN2026 I returned to the dealership for my 2000mi check-in, at ~37,800mi, and was informed that my vehicle had failed the consumption test. With over 600,000 vehicles recalled since 2024 in the 6.2L category, my vehicle/VIN has never been associated with a recall. Despite having minimal miles on this engine, I am now financially penalized for repairs because I had just exceeded the initial Powertrain Warranty and my extended warranty would not cover a pre-existing condition. GM’s 6.2L engines have pre-existing issues from the factory and represents a danger to consumers and the driving public because of these failures.

Dashboard lit up with engine light and stated that there's no compulsion

There is a water leak in the rear passenger compartment of my vehicle. Unsure where water is coming from. Continued leaking poses a risk to my safety as I may be exposed to black mold as well as anyone else who is riding in my vehicle. The problem hasn’t been addressed by the dealer yet but this is a known issue. At this point I have spoken with a representative from the service department at the dealership but cannot get an appointment for several weeks. I was also advised that the problem would need to be diagnosed before being addressed at my cost due to being outside of the warranty period. There were no warning lights or any other signs that this is occurring and was only discovered because I was putting something in the back seat on 6/26/26.

2021 GMC Sierra after purchase at 4,700 miles had issue with the lifter rods and were replaced at that time. Now the truck has a little over 67,000 miles and once again have the same issue. This appears to be a known issue with this truck and the 5.3L engines. The truck is in repair and since it is slightly over its warranty of 60,000 miles. The dealer will not cover the repair. Seeing that this is an ongoing and known issues with service bulletins it seems that this should be a potential recall. We were lucky that we identified the issue early and were able to get to the dealer to fix. Otherwise we could have broken down in the middle of our daily commute in the expressway.

When I put the vehicle in park, the dash warning says it is not in park or shift to park. The components continue to work. I have taken it to the dealership and according to the service manger, this is a very common occurrence in these trucks. This seems to me that it would be a very serious safety issue if one assumes their vehicle is in park and it is actually not. The shift to park warning is a safety warning to alert the driver it is not in park so the vehicle doesn’t roll off and hit someone (especially a child playing in the driveway). Assuming that alert is just a malfunction could get someone killed. I did notice that this was considered a safety recall for some models of GMC vehicles but not others. I’m not sure why there hasn’t been a recall on these trucks when the service manager specifically said they are having this issue on a lot of trucks.

My truck went into Reduced Power Mode while driving on the highway (Very Dangerous and life threatening) for a Coolant Control Valve Failure code (P1098), which has been confirmed by a GM dealership. GM already has extended the warranty for Special Coverage N252508341 for selective Vin numbers only and my Vin number is being excluded which isnt safe at all or fair. My truck is a 2021 Sierra Denali 3.0L lm2 duramax and has the same exact problem (coolant control valve failure code), and the same exact faulty part, and the same exact motor (LM2) which directly matches the perimeters for the N252508341 Special Coverage Program but my truck isnt being recalled or covered for repair due to them selectively choosing certain Vin numbers to recall only.

While driving, the vehicle experienced a sudden and momentary loss of power, similar to briefly applying the brakes, after which power resumed. This was followed by a progressively louder squealing noise. I pulled over to investigate, at which point the engine shut off and a low oil pressure warning appeared on the dashboard. The vehicle would not restart. The vehicle was then towed to a dealership, where initial inspection suggested the issue may be related to the L87 recall involving the crankshaft bearing.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed, but the vehicle continued to move forward. There was no warning light illuminated. The vehicle was taken to the dealer and was diagnosed with transmission failure. The contact stated that the valve body and torque converter needed to be replaced. The dealer informed the contact that the transmission might need to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 65,561. The VIN was unavailable.

The AFM caused piston flapping and other major engine problems such as abnormal wear. The problem with the engine could have caused a catastrophic failure along the side of a highway. The problem has been diagnosed and the engine has been replaced at my expense. The repairs were made at a local mechanic shop. The engine would start make a loud ticking noise at 2000 RPM or above. The mechanic shop referred to this as piston flapping. This was caused by inadequate oil pressure at all cylinders due to the Active Fuel Management.