general problems of the 2021 GMC Sierra 1500 - part 2

The failed component is the engine coolant control valve on a 3. 0l duramax truck. The failure has been documented and confirmed by both an independent mechanic and an authorized dealership. The malfunction creates a significant safety hazard. Without warning, the truck will suddenly enter a reduced engine power mode while traveling at normal highway speeds. When this occurs, the vehicle will not allow acceleration beyond approximately 50 miles per hour. This is especially dangerous when operating on roadways with speed limits of 70+ mph, as the sudden and unexpected loss of power places myself and surrounding motorists at risk. The problem has been reproduced and confirmed by steele GMC in round rock, texas. In addition, the vehicle has been inspected by an independent mechanic, both of whom verified the coolant control valve failure. Prior to the initial occurrence of the failure, there were no warning signs. Once the malfunction occurred, the check engine light illuminated. General motors has issued service bulletin #25-na-185 (revised December 4, 2025), which addresses engine coolant control valve failures on 3. 0l duramax vehicles and outlines the proper diagnostic and repair procedures for this exact failure mode. This bulletin applies to 2021–2026 3. 0l duramax trucks. Additionally, gm has implemented special coverage program n252508341 for 3. 0l duramax coolant control valve failures, which extends coverage up to 15 years or 150,000 miles when diagnostics confirm the failure condition. Despite the fact that my vehicle’s documented failure matches the exact conditions described in the above-referenced service bulletin and special coverage program, I was informed by steele GMC that my specific VIN is not included in the warranty. Given the documented safety risk, the confirmed diagnosis, and the existence of official gm guidance addressing this precise issue, I respectfully request this be reviewed and appropriate coverage or corrective action be authorized.

Engine lifters bent a pushrod and scratched my camshaft in my engine causing me to be stranded with minor children. 3rd time since I bought this in 2021 that I have had engine faults in this truck.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently lost motive power. The contact was able to pull over to the shoulder of the roadway, where the vehicle failed to restart. No warning lights were illuminated. The vehicle was not taken to the dealer or an independent mechanic. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA campaign number: 25v274000 (engine and engine cooling); the VIN was included, but parts were not yet available. The manufacturer was not notified of the failure. The failure mileage was 60,000.

The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA campaign number: 25v274000 (engine and engine cooling); however, the part to do the recall repair was not yet available. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure.

Coolant control valve failure. Instantly reduces power on truck. National back order on parts. No remedy.

The contact owns a 2021 GMC Sierra 1500. The contact stated that the engine was previously replaced under warranty. The contact stated that the vehicle had been experiencing excessive oil consumption and required three quarts of oil every 30 days. The contact received notification of NHTSA campaign number: 25v274000 (engine and engine cooling); however, the part to do the recall repair was not yet available. The contact stated that while driving 70 mph, the vehicle shuddered abnormally and there was an abnormal metallic sound coming from the engine before the vehicle lost motive power. There was no warning light illuminated. The contact was able to pull over to the side of the road. The vehicle failed to restart and was towed to the residence. The local dealer was contacted and informed the contact that a service advisor would return the call. The vehicle was not diagnosed or repaired. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was not made aware of the failure. The failure mileage was approximately 129,000.

? background: •2021 GMC sierra denali – 6. 2l v8 •VIN included in gm’s engine defect recall (connecting rod/crankshaft) •recall status shows “no current remedy available” •defect acknowledged by gm can cause “engine damage, loss of propulsion, or complete engine failure. ” timeline of events: •~1 month ago – truck began running rough with noticeable ticking/knocking noise. •dealer could not schedule appointment for 3 weeks. •08/08/2025 – dealer inspection confirmed failed lifters and damaged camshaft. •repair estimate: $9,300 (see attached dealer estimate). Connection to recall: •lifter and camshaft are internal engine components dependent on the same lubrication and oiling system as the crankshaft/connecting rods cited in the recall defect. •the defect’s potential to contaminate oil and cause internal engine damage makes this failure consistent with recall-related damage.

This recall has been coming for some time now its out and gm still has no plan or action. This is our only auto and my understanding if this issue happens it could cause loss of life. I am concerned for my wife driving to work every day and what happens if we want to take a trip. We need resolution on this. Apr 24,2025 manufacturer recall numbern252494000 NHTSA recall number25v274 recall statusrecall incomplete, remedy not yet available [xxx] 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. While the contact's husband was driving at an undisclosed speed, the contact noticed an abnormally bumpy ride. The contact felt as if the vehicle was driving over rocks. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The contact received notification of NHTSA campaign number: 25v274000 (engine and engine cooling); however, parts were not yet available for the recall repair. In addition, the contact stated that the vehicle had been at the dealer for more than two months awaiting parts. The manufacturer was made aware of the failure and a case was filed. The failure mileage was approximately 80,000.

I receivd a recall on my 2021 GMC denali 1500 , 6. 2 engine recall # n252494000. Made an appointment with carroll GMC, at 1455s. Tamiami trail, venice , FL, on 7/29/25 at 11am. I showed up for my appointment and they denied checking my truck on the recall stating they did not have the remedy to fix the problem so therefore they were not going to check my truck for the recall. . . . . . I have a trip coming up and now I a afraid to go on the highway in case my truck loses power and I get in an accident. . . . . . . . . . . . My truck should have been checked for the recall regardless of the remedy to fix it. . So at least I know weather it is safe to drive or not.

I own a 2021 GMC denali with a 6. 2l v8 l87 engine and 45,500 miles. I have confirmed the presence of metal shavings in the oil and oil filter, indicating that the engine is beginning to fail. When I took the vehicle to my local dealership, I was informed that there is currently no fix for this issue and was advised to continue driving the vehicle. This poses a serious safety risk—not just to me and my family but also to others on the road. A sudden loss of power could lead to a dangerous accident, and I do not want to be responsible for something preventable that could harm innocent people. My concern is that gm is aware of this engine issue but has instructed me to keep driving the vehicle, despite the known defect. How can gm be allowed to avoid accountability for such a critical safety matter? if a fatal accident were to occur, would the responsibility fall on gm or the NHTSA for failing to act? it’s also troubling that gm continues to profit by selling new vehicles, including the 2025 models, with similar issues, all while neglecting to provide solutions for affected customers like me. I purchased this $80,000 truck in good faith, but now no dealer wants to trade or buy these trucks without me taking a significant financial loss—something gm should be responsible for. As a taxpayer, I find it unacceptable that we bailed out gm in the mid-2000s, yet they continue to disregard accountability for their actions. I urge the NHTSA to take this issue seriously. A specific deadline should be set for gm to resolve this issue, and they should face daily penalties for every day they fail to provide a fix. If no resolution is possible, full refunds should be mandated. Please address this issue promptly, as it affects real people’s safety and financial well-being every day.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle stalled, lost motive power, with smoke coming from the engine compartment. There was no warning light illuminated. The vehicle was towed to the residence. The contact attempted to start the vehicle and noticed a knocking sound coming from the engine with the check engine warning light illuminated. The contact received notification of NHTSA campaign number: 25v274000 (engine and engine cooling). The dealer was contacted and informed the contact that parts were not yet available. The dealer informed the contact that the vehicle had a salvage title and would not be repaired under the recall. The manufacturer was made aware of the failure and a case was opened. The failure mileage was approximately 48,000. VIN tool confirms parts not available.

The coolant control valve (part # 24001355) has failed. Apparently this is the case with many vehicles and gm will not/can not get replacement parts. This should be a recall.

The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA campaign number: 25v27400 (engine and engine cooling). The vehicle was taken to the dealer, where the contact was informed that the vehicle failed an inspection. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. In addition, the contact was advised that parts were not yet available. The contact was advised that it was unsafe to release the vehicle to the contact with the recall unrepaired. The contact was advised that the repair would take two weeks for completion. The contact stated that the vehicle had been at the dealer for more than two months. The manufacturer was made aware of the issue but provided no assistance. The contact stated that he needed the vehicle to use. The contact was advised that the vehicle was number 1,000 on the list for the repair. The failure mileage was 71,000.

Wn a 2021 GMC Sierra 1500 6. 2l (VIN: [xxx] ), which is now experiencing a severe misfire, engine ticking, and diagnostic code p318a. I’ve confirmed this issue is related to gm recall n252494001 for engine connecting rod/crankshaft failure. However, I’ve been told my VIN has not yet been activated for recall repairs, and both the local dealership and GMC support have refused to escalate my case or offer assistance. This is a known safety issue, and I’m now at risk of total engine failure and significant financial loss while waiting for gm to act. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

When I started my truck in the morning I noticed the check engine light came on and my engine fan started running really loudly. I shut my truck off and let it sit for 5 minutes and restarted it in hopes the check engine light would not appear. Unfortunately it did come back on and the engine fan began running really loudly again. I drove the truck to the nearest mechanic and you could feel the truck was trying to counter the problem by forcing me to drive it in a lower speed. After taking it to a shop to get it scanned to see what the code was. The mechanic said it was reading code p1006 three times. He said this coolant system and is why my engine fan was triggered to run really loudly. But the engine was not over heating as all other indicators showed that temps were normal. The mechanic believes it could possibly just be a faulty wire. However after talking to gm he said if it is this coolant part that needs to be replaced, it could take up to months to fix as the part is on national backorder. Doing more research, it appears others have had this same problem and gm even knew shortly after this model was released that this would happen.

The contact owns a 2021 GMC Sierra 1500. The contact stated that there was an abnormal change with the rpm. There were no warning lights illuminated. The contact received notification of NHTSA campaign number: 25v274000 (engine and engine cooling); however, the part to do the recall repair was not yet available. The local dealer was contacted. The dealer received an email from the manufacturer, but the verbiage was incorrect to move forward with the repair. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The failure mileage was approximately 39,000. VIN tool confirms parts not available.

Complete engine failure on July 17, 2025, related to current recall for defective engine parts on 6. 2l v8 l87 engine. Towed to dealer same day. Dealer continues to report no eta available on replacement engine. Dealer has had possession of my unrepaired truck for 46 days now and counting.

See attached document for complaint.

This vehicle experienced catastrophic engine failure while I was on vacation 400 miles from home. I have researched this failure and there is a class action lawsuit against GMC. My truck has been at the dealer for 25 days and still waiting for authorization from fidelity warranty services. Considering it’s such a common problem I feel GMC should be paying for this. At the very least the warranty company is aware of this problem and purposely delaying the authorization to repair. I just bought a new camper which I cannot use. I am fisherman and cannot use my boat. My beach pass is also on the vehicle. So essentially my summer has been ruined by a company that produced a faulty vehicle and didn’t discord this information to me.

My 2021 GMC Sierra 1500 with l87 engine, covered by recall 25v274. None of my local dealers are inspecting for this recall. This truck is my daily driver and I routinely drive on interstates for my work. Gm has been slow to address this major manufacturing defect and has not remedied the problem. My truck is no longer worth what is was previously and is lowering trade in or sale value. I am requesting that gm buy back my vehicle due to ongoing safety risks and loss of value.

The check engine light came on at one point. I took it to figure out why the check engine light was coming on and the scanner indicated that the nox catalyst was below threshold. I researched it and it is a common issue. The check engine light eventually turned off after a couple of days. About 2 weeks later it came back on. I noticed as I was driving the coolant fans were running at 100% meaning that they were blowing long and hard. So I scanned it and it said that the engine coolant valve was at fault. This is also a common issue with the vehicle, particularly in the 2021 GMC Sierra 1500 3. 0 turbo diesel. It is a faulty part and it costs thousands of dollars to replace. How can these two issues not be on a national recall by gm? they are too common and very expensive to repair. This issue is so common that now the valve is on a national back order. Meaning the parts may not be available for 30-120 days. The vehicle is not safe to drive with a bad engine coolant valve. I have now a rental car for the past 7 days while my truck sits waiting for a valve to arrive and pay thousands in repair just to drive it again.

What component or system failed or malfunctioned, and is it available for inspection upon request? the valvetrain system failed due to broken rocker arms, which resulted in additional internal engine damage. This failure occurred under normal driving conditions. The affected components have not yet been discarded and are available for inspection upon request. How was your safety or the safety of others put at risk? the failure caused sudden engine misfiring and knocking, reducing engine power while I was operating the vehicle. This significantly compromised acceleration and response time, especially during merging and lane changes, which could have led to an accident. Any unexpected loss of power or engine instability at highway speeds poses a serious risk to myself, passengers, and other motorists. Has the problem been reproduced or confirmed by a dealer or independent service center? yes. The issue has been diagnosed and confirmed by an independent certified mechanic, who verified the broken rocker arms and resulting engine damage during inspection. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? the vehicle has not yet been inspected by the manufacturer, police, or insurance representatives. Only a certified independent mechanic has inspected the failure thus far. Were there any warning lamps, messages, or other symptoms of the problem prior to the failure, and when did they first appear? yes. The check engine light appeared and the engine began running rough and producing a knocking sound. These symptoms occurred just prior to the confirmed failure and prompted me to stop driving the vehicle immediately and have it inspected. Given the seriousness of this issue and reports from other GMC 5. 3l engine owners experiencing similar rocker arm failures, I urge the NHTSA to investigate this potential defect. It poses a real and significant safety risk.

P1098 code - coolant control valve on/off/on/off.

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving approximately 40 mph, the check engine warning light started flashing and the vehicle was shaking with a misfire coming from the engine. Additionally, there was black and greyish smoke coming from the tailpipe. The roadside assistance request message was displayed on the instrument cluster. The vehicle was taken to a dealer where it was diagnosed with a misfire. The vehicle was not repaired. The vehicle was taken to the residence, but the failure persisted. The vehicle was taken to an independent mechanic to be diagnosed, and it was determined that the lifter had dropped, and the engine needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was unknown.

The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA campaign number: 25v274000 (engine and engine cooling). The contact stated that while driving at approximately 50 mph, there was a loud squeaking sound coming from the front driver’s side of the vehicle before the vehicle lost power. Simultaneously, the check engine warning light started blinking. The vehicle was pulled over to the side of the road and the sound became louder, before becoming a knocking sound. The vehicle was restarted, and the failure persisted. The vehicle was towed to the residence. The vehicle was not diagnosed or repaired, but a dealer stated that there was as recall associated with the VIN; however, parts were not yet available to repair the vehicle. The manufacturer was not notified of the failure. The failure mileage was approximately 128,000. VIN tool confirms parts not available.

Coolant control valve is faulty. Part number 24001355 for my GMC diesel Sierra 1500. The check engine light goes on and sometimes the engine power will be cut in half to protect the engine. It can be inspected when needed. My truck cannot go as fast and the engine fans sound very loud to cool down the engine. I was 3 hours away from my house when this happened the first time and I wasn’t sure I would make it home. I had to let the engine cool down for about 6 hours after I pulled off of the highway. This has happened two times so far and happens when the ac is on and sometimes when you use the remote start it won’t start the truck remotely and the check engine light goes on. The problem started in July 2025 with 51,000 miles. The engine control module code is p1098. I have asked my GMC dealership to look at the issue and they have told me that the part is backlogged for at least 2 months and they will not look at my truck until the part is available. I haven’t had any other issues with the engine so far and this was the first time a check engine light has gone on.

The contact owns a 2021 GMC Sierra 1500. The contact stated that upon starting the vehicle, there was an abnormal knocking sound coming from the engine. The abnormal sound ceased once the vehicle had accelerated; however, the abnormal sound returned while the vehicle was idling. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed that the ball bearing caused a misfire, and two cam lifters needed to be replaced. The vehicle was repaired. The contact picked up the vehicle and on the way home, the engine failed. The contact took the vehicle back to the dealer. The technician test drove the vehicle with the contact as a passenger, and the check engine warning light illuminated. In addition, there was an abnormal sound coming from the engine. The vehicle failed to accelerate as intended while depressing the accelerator pedal. The contact was informed that the engine failed and needed to be replaced along with the fuel body system. The contact was informed that as per GMC, the oil needed to be changed to an oil with a thicker viscosity. The fuel body was replaced, and the oil was changed. The manufacturer was made aware of the failure and offered the contact an amended warranty. The contact was informed that GMC had elected to participate in the procedures under the song beverly act. The failure mileage was approximately 50,000.

See attached document for complaint. I am writing as the owner of a 2021 GMC Sierra 1500 equipped with the 6. 2-liter engine that has recently been included in a significant recall. I've been advised that the engine may need to be replaced entirely. As you can imagine, this is extremely concerning given the scale of the defect and the vital role this truck plays I'n my dayto- day responsibilities.

The contact owns a 2021 GMC Sierra 1500. The contact stated that upon starting the vehicle, the vehicle was idling abnormally, prompting the contact to turn off the vehicle. The contact stated that the check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the lifter in cylinder #4. The contact stated that the lifter had collapsed into the engine, causing damages to the engine and camshaft. The vehicle was repaired. The manufacturer was not notified of the failure. The failure mileage was 98,000.

The contact owns a 2021 GMC Sierra 1500. The contact stated that after driving on a trip, the contact noticed that the vehicle had lost 10 mpg after a software update was performed. The check engine warning light was illuminated. The vehicle was taken to richardson Chevrolet (3825 s huron rd, standish, mi 48658), who confirmed that the vehicle was working as designed. The check engine warning light was reset. The vehicle was not diagnosed or repaired. The manufacturer was contacted and opened a case, and referred the contact to the NHTSA hotline for assistance. The failure mileage was approximately 57,000.

The coolant control valve on my truck is causing issues. From doing research, this is an ongoing issue with the 3. 0 duramax. The part is on nationwide backorder and I cannot drive my vehicle in reduced engine power because the only way I can get to work is by taking the interstate. It is madness that gm has not issued a recall or done anything to rectify this issue. Many GMC owners are paying on vehicles that they are unable to drive which is assanine. This part needs to be readily available due to the numerous complaints that have already been submitted in regards to this part.

My 6. 2 engine locked up and left me stranded. Had it replaced with s new engine on 10/31/2025 and I'm having problems again with it. As well as my 10 speed transmission slipping and hunting for gears.

Have owned my 2021 GMC Sierra 1500 with the 3. 0 duramax for a year and the check engine light has come on multiple times for a "coolant control valve" issue. The truck runs the fans at 100% and puts the truck into reduced power at least once a day. I have read that gm sometimes will not cover this repair under powertrain warranty even though it's an engine problem. Please fix this issue! to answer the previous questions, the coolant control valve is malfunctioning, and the truck is currently at the dealer being inspected. Yes the dealer has said this issue is common on these trucks (confirmed by national GMC in american fork, utah). Yes the check engine light has appeared multiple times. These issues started appearing in June 2025.

Was informed from by gm that my vehicle is involved with a recall an still hasn't been repaired.