Complaint volume
436 consumer-submitted complaints are matched to this model year. Treat the count as a research signal, then read the actual summaries for repeated symptoms.
Complaint records
2020 GMC Sierra Complaints
436 consumer-submitted complaints on record for the 2020 GMC Sierra, grouped by component category.
436 Total complaints
11 Crash reports
5 Fire reports
6 Injury reports
Complaint data reflects consumer-submitted reports. A complaint is not proof
of a defect, recall, or manufacturer fault. Enriched severity fields come
from official bulk records when the complaint can be matched by ODI number.
Buyer interpretation
How to use these complaints before buying
Complaint records are most useful when they turn into inspection points, seller questions, and comparison checks against nearby model years.
Pattern to inspect
The most common categories are engine, power train, electrical system. Use those categories as a test-drive checklist instead of judging the vehicle from the total count alone.
Severity flags
Enriched records include 11 crash reports, 5 fire reports, 6 injury reports, and 0 fatality reports. These fields come from complaint records and should be read in context.
Mileage clue
Mileage is available on 121 complaints, with an average reported failure mileage of 45,188 miles. Compare that with the mileage on the listing.
Questions to ask the seller
- Have you had any problems related to engine, power train, electrical system?
- Can I see recent maintenance and repair records?
- Has the vehicle ever been towed, involved in a crash, or repaired for the same issue twice?
- Can we also check the recall record for this 2020 GMC Sierra?
Used-car checklist
Use these complaints before the test drive.
Build a buyer checklist to turn these issues into questions and inspection points.
2020 GMC Sierra
Build buyer checklist Compare with other years Sends year, make, and model to pre-fill your checklist.
How severe are the 2020 GMC Sierra complaints?
11 Crash
5 Fire
6 Injury
0 Fatality
29 Towed
4 Medical attention
What are the most common 2020 GMC Sierra complaint categories?
ENGINE 130
POWER TRAIN 38
ELECTRICAL SYSTEM 22
POWER TRAIN,ENGINE 17
SERVICE BRAKES 16
STEERING 14
UNKNOWN OR OTHER 14
ENGINE AND ENGINE COOLING 10
SUSPENSION 9
ELECTRICAL SYSTEM,ENGINE 8
436 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| Aug 2025 | ENGINE,FUEL/PROPULSION SYSTEM | For approximately the last year (2024-2025) my 2020 GMC Sierra 1500 AT4 with the 6.2L engine has had noticeable ticking, knocking, and unprovoked shaking upon start up and idle. The pickup has stalled out at stop lights and intersections in the past, posing risk. In June (2025) the pickup was taken to a certified mechanic for inspection who suggested possible lifter or valve failure. The vehicle exhibits a persistent ticking sound from the engine, which I believe may be related to lifter or valve issues, similar to those reported in lawsuits against GM for 2019-2024 models and the recall for 2021-2024 models (NHTSA Recall ID: 24V-676). This ticking occurs regularly, including at approximately 54,500 miles, and raises concerns about potential engine failure or sudden loss of propulsion, which could be hazardous, especially at highway speeds. I have noticed approximately 2 quarts of engine oil usage per my last 2 oil changes (roughly every 6,000 miles). I recently had taken the pickup to a local GM dealership where they informed me that I am not longer covered under warranty and the recent recall is not applicable. I was advised to “keep and eye on it, and get a AAA membership”. I am aware of at least 10 class action lawsuits against GM for similar engine issues in vehicles like mine, suggesting a widespread defect. These issues, combined with the potential for engine failure or impaired vehicle control, warrant investigation to ensure driver safety. I have records of the ticking sound and can provide further details if needed. I am willing to cooperate with NHTSA for inspections or further documentation. | Crash: No Fire: No | Unknown |
| Aug 2025 | ENGINE,ELECTRICAL SYSTEM,EQUIPMENT | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving with cruise control mode set at 55 MPH, the vehicle independently accelerated to 98 MPH, and then the vehicle lost motive power. Additionally, the contact stated that the vehicle had failed to turn off upon pressing the Engine Start/Stop button. No warning light was illuminated. The vehicle was able to restart and was taken to a local dealer to be diagnosed, but the cause of the failure could not be determined. Additionally, the contact noticed that water was leaking inside the vehicle through the rear window on rainy days. The contact stated that the infotainment screen had failed to turn on as intended on some occasions, and the screen had displayed a rearview camera image while the vehicle was in drive(D) on other occasions. The contact stated that while driving at various speeds, the transmission made an abnormal sound, and the RPMs failed to decrease as intended, but suddenly dropped while decelerating. Additionally, the contact stated that the headlights, the fuel pump, and the main pulley were replaced at the local dealer. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 250. | Crash: No Fire: No | 250 |
| Jul 2025 | ENGINE,FORWARD COLLISION AVOIDANCE | My GMC had a terminal engine failure around 5/3/25. This disengaged the ESC, parking brake, and driver assist abilities as well as making the truck undrivable. GMC service diagnosed the truck needed an entire new engine. The repair took over 2 months to complete and now that I have the truck back, the adaptive cruise control is not working. | Crash: No Fire: No | Unknown |
| Jul 2025 | ENGINE | Check engine light came on. Cooling fan for engine running none stop. Reduce power mode from engine. Took to dealer, said it’s the coolant control valve. Dealer said the part is on back order and don’t know when they will get it in. Looked up the issues and sounds like many people are having the same problem with the 3L diesel from GMC. These people reporting the same thing and having to wait months for the part. My truck was just out of warranty by 200-300 miles | Crash: No Fire: No | Unknown |
| Jul 2025 | UNKNOWN OR OTHER,LANE DEPARTURE,BACK OVER PREVENTION | 1. Lane Keeping Assistantance: The green vehicle indicator on the dashboard will disappear and stay off while driving. When it is off, it is unsafe. 2. Parking Collision Warning: The front and back sensors will disappear and become nonfunctional while driving and parking. Sometimes they activate for no reason as well. 3. Both exterior mirrors: After starting the engine to drive off , both exterior mirrors will lower automatically from my setting. After the truck is started and driven off, they must be rest again. | Crash: No Fire: No | Unknown |
| Jul 2025 | STRUCTURE,UNKNOWN OR OTHER | My multipro tailgate on my 2020 GMC Sierra 1500 unlatched while a trailer was attached and backing up said trailer. The trailer jack post proceeded to buckle the upper part of the tailgate assembly causing extensive damage resulting in over a three thousand dollar repair bill. If the tailgate had released while a child was in close proximity, serious injury may occur. The tailgate has inadvertently released twice in the five plus years I have owned it, the first time as I was traveling down a highway at over 60 mph. This could have endangered a vehicle to my rear if cargo had been released on to the road. I have reached out to a local dealership for repairs and assessment, no real way of troubleshooting something that has happened twice in five plus years. The scan did not show any codes. the info center does notify you if it is released but not before it takes place and after the fact may be too late in some circumstances as it was during the second occurrence. There has been a recall on 2500 and 3500 models with the exact same tailgate but not the 1500 models. 820K vehicles affected but not on the 1500's. | Crash: No Fire: No | Unknown |
| Jul 2025 | ENGINE | On June 19th, 2025, I was driving to work when my truck began to lose power, and the check engine light came on. The error on the display is Loss of Engine Power. I took it immediately to Oreilly's so they could run the free engine light check. When they got the report, the employee was amazed that there were over 45 problem codes showing up. As I drive the vehicle there is a pull back from the engine before it starts to pick up speed. On braking as well there is a little kickback before it comes to stop. It takes more foot pressure to pick up speed. The Truck using up more fuel because of this issue. I took the truck to a local certified mechanic, and he ran the diagnostics as well and it came up with the over 45 problem codes as well. His recommendation unfortunately was to take into the dealership so they could check it and see if they have a solution for this engine malfunction and error codes. | Crash: No Fire: No | Unknown |
| Jul 2025 | ENGINE | Engine overheating at 50,000 miles. Temp would intermittently jump up to 230plus degrees while driving. Radiator replaced per dealership diagnosis. Issue still happening. | Crash: No Fire: No | Unknown |
| Jun 2025 | ELECTRICAL SYSTEM,ENGINE | Woke up one morning and the entire back seat, entire truck flooring was soaking wet. Got it to Gerber collision in El Reno, Oklahoma. They said that the back window had a crack in it. My insurance said it is a mechanical issue on the sliding back glass and they do not cover such issue. Also want to turn in that the transmission in this truck had to be replaced two week prior to this incident. The truck only had 118,000 miles on it. Safe to say that this 10 point GMC diesel truck is a nightmare and the entire truck is a hazard. They need to take these truck off the market. | Crash: No Fire: No | Unknown |
| Jun 2025 | POWER TRAIN | I had the rear wheel recall done not long ago and 2 days ago my transmission shuddered. | Crash: No Fire: No | Unknown |
| Jun 2025 | SERVICE BRAKES | I will start by saying that I have had this issue since I had the truck (2020), less than 10k miles. I mentioned to the dealer multiple times. I was told that they can't figure it out since it has to be doing it while it is at the dealership to figure it out. I am finally fed up with that answer. The issue is with trailering. It will randomly lose trailer brakes while driving down the road. Sometimes the brakes will come back right away, sometimes they will not. Other times other lights that should be working will randomly stop working as well such as turn signals. This has happened multiple times and I only tow a few times a year when I pull my travel trailer. I have a video of it doing it as I am driving down the road. For the additional details with approximate date that this incident occurred, I will put the last date that this was found. | Crash: No Fire: No | Unknown |
| Jun 2025 | ELECTRICAL SYSTEM | Power Steering works sometimes and then stops Trailer Break system issues | Crash: No Fire: No | Unknown |
| Jun 2025 | ELECTRICAL SYSTEM,ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving on a main road at 40 MPH, the vehicle lost automotive power, causing the vehicle to shut off. There was no warning light illuminated. The vehicle was towed to a local dealer where the vehicle was diagnosed, and the contact was informed that the engine wiring harness was faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 80,000. | Crash: No Fire: No Towed | 80,000 |
| Jun 2025 | ENGINE | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment before the vehicle lost motive power with the check engine warning light illuminated. The vehicle was towed to the residence. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The dealer referred the contact to the manufacturer for further assistance. The manufacturer was made aware of the failure. The approximate failure mileage was 138,000. | Crash: No Fire: No Towed | 138,000 |
| Jun 2025 | VISIBILITY/WIPER | The rear back glass is leaking water excessively in to the inside of the vehicle when it rains or gets washed. The vehicle is available at any time for inspection. The amount of condensation that accumulates on all the interior windows makes it impossible to see out of the vehicle. The defrost can not handle the amount of moisture build up. The Dealer knows about this condition and it has been verified by a window company. The manufacture knows and understands there is a problem and has put out a Technical Service Bulletin ( TSB 18‑NA‑383 ) for this issue but will not cover the repairs. GM knows that every single vehicle with this window designs from 2019-20121 will leak just outside the 3 year 36k mile warranty coverage. The cost of repair is approximately $2k. Dealer will not cover repair. | Crash: No Fire: No | Unknown |
| Jun 2025 | STEERING | While driving vehicle at normal speeds the steering assist goes out and becomes very hazardous to drive. It is intermittent and does not do it all the time. When connected to dealer diagnostic machine it throws several codes. I have read on several GM sites this problem is widespread and GM is actively saying they haven’t heard of this problem. When the problem occurs it is almost impossible to control the truck to get over to the side of the road. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | I own a 2020 GMC Sierra 1500 with a 5.3 liter engine..... My engine lifters failed at 105,235 miles.... Lifter broke and damaged the Cam Shaft to a point that required full engine replacement costing me $10,800. When I asked GM for help, they denied because I went to a local repair shop with certified mechanics. I believe GM is fully aware of this problem and they are ignoring I think GM should pay for at least half of my repair bill. Thank you! | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | Engine failure/ lifter issue with no prior warning. Driving down the road vehicle suddenly lost power and error message appeared. The vehicle was inspected by GM dealer and extended warranty company in late 2023. We no longer own this vehicle | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | My engine slowed down on the interstate. My steering wheel was visibly shaking and I lost the steering access control. The truck threw an Cylinder 6 error code. At the mechanic, they identified that at least one of my camshaft lifters had failed. If I had continued to drive my vehicle, the engine block would have eventually locked up. | Crash: No Fire: No | Unknown |
| Jun 2025 | SERVICE BRAKES | I was driving my 2020 GMC Sierra 1500 on a local street when the dashboard suddenly displayed a “Brake Failure” warning. I immediately realized I had no braking power and had to safely roll into an uphill parking space to stop the vehicle. While waiting for the tow truck, I researched the issue and discovered there is a known recall related to the brake calipers on some 2020 Sierra 1500 models. However, when I entered my VIN, it showed no open recalls. I also contacted GMC directly, and they confirmed that there are no active recalls associated with my vehicle. Additionally, the vehicle's onboard information system indicated that the front brakes were at 65% and the rear brakes at 80%, suggesting that brake wear was not a contributing factor. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE | I took my 2020 GMC Sierra 1500 to the dealership after Cylinder #5 seized while driving, and I was forced to replace the entire engine. At the time, I contacted the dealer and was told there was no recall related to this issue. However, I have since learned that GMC has issued a recall for similar engine problems affecting 2021–present Sierra 1500 models, but not for my 2020 model year. I believe this issue may be related and would like further investigation and consideration. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment and the vehicle then failed to exceed 30 MPH. No warning lights were illuminated. The vehicle was taken to the dealer, who were unable to determine the cause of the failure. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); but the VIN was not included. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline for assistance. The failure mileage was 90,000. | Crash: No Fire: No | 90,000 |
| Jun 2025 | ENGINE | Vehicle currently has 104K and needs a 3rd engine. The same issue happened to the second engine as the first. While Driving the engine just stop working. They say it is a problem with the camshaft. Metal gets into the transmission and that also has to be replaced. A vehicle engine should not just stop working! Especially on an interstate. GMC refuses to add this engine to the recall list. However, I don't understand how the safety of families can continue to be placed in jeopardy. | Crash: No Fire: No | Unknown |
| Jun 2025 | ENGINE,FUEL/PROPULSION SYSTEM | Transmission has slipped and shuddered multiple times. We have had it diagnosed at gmc dealership and our mechanic, advising that it is 8L90 transmission failure. It will slip to lower gear abruptly, causing for possible safety issues especially on the highways. | Crash: No Fire: No | Unknown |
| Jun 2025 | POWER TRAIN,UNKNOWN OR OTHER,ENGINE | 1. On 05/9/25, the exhaust emissions system malfunctioned, triggering diagnostic trouble code P2C7A (exhaust emissions system failure). This repair, the seventh attempt since June 2024, addressed the same recurring emissions issue previously involving replacements of components such as the NOx converter (02/18/25, 03/13/24) and EGR valve (02/18/25). The vehicle is available for inspection upon request. 2. The P2C7A failure risks limp mode, reducing vehicle power unexpectedly, which is hazardous on highways, especially while towing. Exhaust emissions system malfunctions release excessive pollutants, posing environmental and health risks to others. 3. Yes, the P2C7A code was confirmed by dealer during the 05/9/25 repair, following prior confirmations (e.g., 03/31/25–04/05/25. 4. The vehicle was inspected by Young Chevrolet-Cadillac during multiple repairs (e.g., 03/31/25, 05/9/25). 5. Yes, the check engine light and OnStar emissions alerts appeared prior to the 05/9/25 repair, first noted ~June 2024 (P2C7A onset). Exhaust smell and reduced fuel economy were observed intermittently. Symptoms persisted post-03/31/25 repair, leading to the 05/23/25 service. | Crash: No Fire: No | Unknown |