This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.
So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.
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.
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)
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.
The coolant control valve is faulty and is on national backorder causing months of my truck sitting in the shop. This is not an isolated issue. GM is claiming it is not covered under warranty, but the part design is clearly a serious issue.
The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 75 MPH, the vehicle jerked and downshifted to overdrive. The message "Engine Power Reduced" was displayed on the instrument panel. The driver depressed the accelerator pedal, but the vehicle failed to exceed 4 MPH. The vehicle was taken to the dealer, where it was diagnosed that the valve body failed, which caused the transmission to fail. The vehicle was repaired. While the contact was driving home after the vehicle was picked up, the vehicle jerked and hesitated. The dealer was contacted and informed the contact that if the check engine warning light becomes illuminated the vehicle could be diagnosed. After several days, the check engine warning light illuminated, and the vehicle was taken to the dealer where it was diagnosed that the shutter valve had failed and needed to be replaced. The vehicle was repaired. The contact stated that the failure persisted. The contact received NHTSA Campaign Number: 24V797000 (POWER TRAIN). The vehicle was repaired; however, the failure persisted. The manufacturer was made aware of the failure and offered the contact assistance with the transmission repair. The failure mileage was approximately 119,000.
- Saint Michaels, AZ, USA
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My 2021 GMC Sierra 1500 Diesel Truck is displaying the Check Engine Light which I was told by the local Mount Vernon GMC Dealership is a failed Temperature Control Valve affecting the transmission. I also get a warning message of "Reduced Engine Power". I am told that it is OK to drive the vehicle but at reduced power. The dealership told me they ordered a replacement part which is covered under warranty on May 7, 2025, but showed on "Back Order". Every time I call to follow up on the status, I'm told it is still on "Back Order", and they cannot do anything to improve the delivery. Why does a customer, owning a "Denali" truck under warranty, can't get the problem resolved" I have a recall notice from GMC dated January 2025 about this very problem and have shown it to GMC dealerships during regular services, and still have the problem. Since I have bought this truck, I have experienced a failed right running board that cost $1,500 to repair a few months ago which is failing again. The driver side mirror now vibrates when I put the truck into drive after being in reverse, and I cannot get any idea on when this transmission valve problem will be fixed which is causing me serious delays in using the truck to pull a trailer. Prior to this problem I had the dealership replace my brakes which required 2 follow-up repairs due to the "GMC original rotors" being warped that required machining to make them not vibrate which to me, now makes them "used". This means I paid full price for "repaired" parts! I thought that by buying a GMC "Denali" 1500 Sierra truck I was buying the "top of the line" in pick-up trucks but now finding out it's a lemon. I love the truck, but not the problems. What do I need to do to get this fixed" [XXX] [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
In December of 2024 the engine started not being able to reach full power. This would happen intermittently and there would be a check engine light that would come on when this was happening. In January of 2025 I had the code pulled up by a mechanic at a local shop and this mechanic actually spoke to the service manager of the GMC dealership who said it was covered under the 100,000 mile power train warranty. I took it to the dealership who then told me the diesel mechanic was backed up and I would have to schedule repair for February. I had also received a recall notice in the mail for another issue so asked about taking of both things at the same time. I made the appointment for mid-February so had to deal with reduced engine power for several weeks.The dealership had my truck for several days and a recall was fixed and I thought the reason for the reduced engine power had been fixed also. I had received a phone call from the service representative about an issue that would cost over $1200 that I declined. I did not realize that this was actually for the main issue. I was still thinking the reduced engine power was under warranty. I got my truck back but then the next day the check engine light came on again and the engine power was reduced again. I immediately called the service representative who then told me only the recall had been fixed and that the reason for the reduced engine power was not fixed because I had declined the service. I was totally confused and didn-??t understand what happened. This is when I was told that the reason for the reduced engine power was due to a coolant control valve, which was not under the powertrain warranty. I pushed the issue and wanted answers as to why the service manager himself told the mechanic that it was under warranty and was told that the service manager is not a technician and they rely on what the technician says is the problem. And this problem was not covered. I finally gave in and got it fixed and paid $1788.
coolant control valve failure activating check engine light, reduced power mode and fan running continuously. Truck has been in the shop for 3 weeks already with no part available.
The contact owns a 2021 GMC Sierra 1500. The contact stated upon starting the vehicle and shifting to drive(D) in the morning, the transmission hesitated to shift to second gear and then shifted harshly. There was no warning light illuminated. The vehicle was taken to the dealer, where it was test-driven, but the failure could not be duplicated. The contact stated that the failure occurred once a day on first start-up of the vehicle and upon shifting to drive(D). The vehicle was taken back to the dealer over the weekend, and the dealer was able to duplicate the failure on first start-up of the vehicle and upon shift to drive(D). The dealer related the failure to TSB Number: 16-NA-361; and informed the contact the manufacturer had not made a repair available. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to file a complaint. The failure mileage was unknown.
received my truck back after replacement of the front transmission pump and idle gear, the same day the transmission had horrible down shifts, sometimes it would just downshift into neutral and bounce off the rev limiter. the service advisor told me that my transmission had to "relearn" my driving habits when I called him and would take 200-400 miles.. i drove it one more day and drove it back to the dealer to have them drive it. the agreed that something was wrong, but didn't know what and had to contact gm engineers. 2 days later they told me that the valve body needs to be replaced. I dropped it off to find out that it had been ordered with zero ETA of when they will receive it.. so now im stuck with a loaner and no ETA on when parts will be available.
Reached the 100,000 mile mark and the truck started shuddering. Took it to the dealership and they tell me the torque converter is coming apart and I need a new transmission.
My truck has a known recall from GMC which results in total loss of propulsion. It has not failed yet, but this is dangerous to me, my family/kids, and potentially others on the road. I have made multiple attempts to speak with GMC about the issue and also my local dealer. Neither group will provide concrete information as to when they can look at/service my truck even though there is a known remedy - [XXX] I brought my car into the dealer December of 2024 for brakes and also a rattling noise since it was uncharacteristic. Noises can be indicative of this larger problem (which I know now and didn't then) but they "didn't hear a rattle" and the "condition could not be duplicated" which is patently false since it still makes the noise/has gotten worse. Since then, I have taken the following actions: - I called and spoke with the local dealer service team on 5/5 - was told since it's showing incomplete, no remedy available there was nothing they could do - Spoke with GMC on 5/5 - they directed me to the local dealership - Made an appointment online on 5/10 to get my truck serviced and to check for this problem - They immediately called me first thing on Monday 5/12 to cancel my appointment and again tell me there is nothing they can do about this issue - I have continued to express my safety concerns to both parties - I spoke to GMC today, 5/30 and was told that there is no timeline for the issue (with my VIN) even though the remedy is known - An appointment is scheduled on 6/12 with my local dealership, but if I recall status hasn't changed, they will not check for this problem INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
front idler gear for the transmission pump failed at 39500 miles. was fixed under GMC warranty. but now after getting the truck back the transmission has extremely harsh down shifts. still waiting for GM to figure out what to do next..
The truck ever since of bought it has been nothing but issues. Starting with the fuel pump issues then electrical issues and most recently the coolant flow control valve. This is my work truck and now I-??m out of a truck with no loaner and the dealership has no eta.
Engine has stopped a couple of times at low speeds, Was able to restart and continue. Engine will occasionally make a "straining / Dieseling sputtering sound" when execellerating from low speeds or Stop. Transmission will make strange and strained shifts from time to time. This is reaccruing problem that comes and goes over the last approximately 2 yrs since about 9000 miles to current approx 25000 miles.
The transmissions in this as well as several other models of GM as well as Ford products with these transmissions are known to have major issues. My particular vehicle has major transmission shipping issues that started right around 90,000 miles or so. It started with a hard shift occasionally and has now progressed to a consistant hard shift, as well as a major shudder issue in the 35-45 mph range as well as the 65-75mph range ( when shifting into applicable gears) this has gotten worse over the last few weeks. These GM/Ford collaboration transmissions have been faulty from their inception and are well known to start malfunctioning in the 80-120,000 mile range. Please recall these transmissions so that consumers are not faced with thousands of dollars in repairs in vehicles that should last well beyond the short life span of the transmissions. I have been quoted 62-6500.00 for a replacement as there is no rebuilding these transmissions according to the mechanics I have consulted...(some have cited part availability issues as a reason). This has been a well reported problem with these vehicles/ transmissions for years now with many complaints and issues about the faulty transmissions. Just google it. I don't understand why theu have yet to be recalled.
The engine coolant flow control valve position sensor is faulty. I brought mt truck in to my dealership and I have been waiting for over a month to get the issue fixed because -??the part is on backorder-??. This issue makes my truck sound like a jet engine because it makes the truck think overheating and causes the fan to come on at full blast. After drivinf for awhile it goes into -?? reduced engine power mode-?? which is totally unsafe because it reduces the horse power to that of a lawn mower. It takes about 30 seconds to get from 0-60, so merging onto freeways or in conditions where you need extra speed its completely useless and increases the scenario of being rear ended, immensely.
Vehicle is diaganosed with a coolant control valve issue. Vehicle is currently at a GM dealer awaitng replacement part and part is on back order for an undertemined amount of time. It is widely known this is a common problem with this make and year model of vehicle. This matter puts an undue hardship on me as a vehicle owner. With no known eta for this part I stand to be out of use of this vehicle for a long time. GM needs to be more accountable and attentive to their customers at a time like this.
El motor de mi camioneta falló por completo empezó a hacerle unos ruidos muy fuertes dentro del motor con solo 80,000 millas es del 2021 la compré el año pasado no llegó ni un año de uso una camioneta que supuestamente era muy buenas Estaba en el momento de lo sucedido estaba con mi mujer y mi hijo en el auto regresábamos de un restaurante acá en Miami y la camioneta se paró de pronto La camioneta fue inspeccionada por la garantía extendida la cual no asumió la reparación Luego del problema si salieron luces amarillas y rojas en la pantalla de mi camioneta
While driving on the highway the engine died forcing me to change lanes to cross traffic and coast to a stop on the shoulder. It was dangerous and unexpected. It would not restart so I had to have it towed. Inspection revealed the bearings had gone bad in the engine and the engine would have to be replaced. I had to wait 2 and half months for an engine.
A D V E R T I S E M E N T S
- Jacksonville, FL, USA