The Most Reliable GMC Sierra Years, And Some To Avoid (According To Owners)

Before Sierra became a full-size truck model of its own in 1988, the name was used to describe an available trim on other GMC trucks. The GMC Sierra has done well in sales despite stiff competition from the likes of RAM, Ford, and Toyota, with over 295,000 units sold in 2023, according to GoodCarBadCar.net. There are many versions of Sierra, such as the 1500, hybrid, and heavy-duty models like the 2500 and 3500. 

We recently strapped in behind the wheel for our 2024 GMC Sierra 1500 Denali Ultimate review and walked away impressed with this luxury truck. While GMC's latest offerings are fantastic, there are also some great earlier models worth checking out. Although not every production year for the Sierra is a good choice when searching for a used pickup.

The GMC Sierra 1500 has changed over each generation, and in terms of reliability, some of the best options are the 2006, 2012, and 2020 truck models. The worst years in terms of problems for this GMC are by far 2014 and 2015, with issues such as shoddy headlight performance, climate control issues, and engine knocking sounds.

According to Kelly Blue Book, owners rate the 2006 Sierra 1500 a very positive 4.6 out of 5 stars, with around a 94% recommendation score. Several owners remarked on the impressive longevity of their truck, with it offering notably predictable and stable performance. Another driver with experience behind the wheel of the 2006 iteration jokingly exaggerated, "[You] could take the engine out of this thing and throw it into the Atlantic Ocean, fish it out 30 years later, then fill the gas tank up with peanut butter and it would start right up." The base engine for the 2006 Sierra 1500 is a 4.3-liter V6, with more robust options like a 4.8-liter V8 for more output.

The complaints about this particular Sierra occurred on average close to the six-figure mileage milestone, with the most significant being rust forming on the brake lines, per CarComplaints.com, and the 2006 Sierra featured some of the fewest criticisms over the last 18 years of production. Consumer reviews on Edmunds.com are also glowing with a 4.2 out of 5-star rating, with a perfect score from more than half of owners.

One of the gripes voiced by owners of some of the earlier Sierra models was noise and ride comfort. With options like the posh Denali trim, this 2012 Sierra was not only more lavish on the inside but also offered a more refined and quiet travel experience. Owners commented that the Denali provided an enhanced and smooth ride that complemented the upscale interior amenities. Some even compared the ride of the Denali to a premium sedan, which is high praise for a robust pickup truck.

In terms of safety, the National Highway Traffic Safety Administration lists only 2 recalls and gave the 2012 Sierra 1500 rear-wheel drive model a 4 out of 5 stars in overall frontal crash protection. One driver had the misfortune to test out the Sierra's safety measures with a terrible accident, and reported, "We were sandwiched between two other vehicles at a stop light. Our 2012 GMC did everything it was expected to from a safety standpoint and saved us from sustaining much worse injuries."

The 2020 Sierra offered one of the best years for the 6.6 Duramax engine, the L5P, in the heavy-duty variants. With around 91% of owners recommending this year on Cars.com, it received high marks in every category, from comfort and performance to reliability and value. JD Power awarded the 2020 Sierra with the title of America's Most Reliable Full-Size Truck After 3 Years of Ownership.

Drivers praised the 2020 model's engine options, ergonomic seating, and tranquil ride. Another advantage touted by owners of this Sierra was the innovative and cutting-edge technology built into it, making the driving experience more straightforward and effortless. We confirmed this sentiment with our 2020 GMC Sierra HD review, calling it a "towing tech powerhouse."

When looking at the various production years, the 2020 features even fewer complaints on CarComplaints.com than the 2006 model, with just a few reports of infotainment issues and one report of a rear window leak. Even after 4 years, sites like Repairpal.com list zero complaints for the 2020 truck.

For an excellent used full-size pickup, don't give the 2014 or 2015 Sierra a second thought. These models received the most complaints, with owners reporting problems with the air conditioner and engine, as well as issues with the headlights.

According to reviewers on Consumer Reports, they experienced several headaches with their 2014 Sierra climate control system pertaining to the compressor, fan, and leaks forming, among other dilemmas. Unfortunately, repairs for some reached upwards of $1100, making it a costly issue to remedy.   

The 2015 Sierra, unfortunately, suffered an odd mechanical noise emanating from the engine and proved to be quite expensive to repair in some cases. One owner learned that their Sierra required new lifters, and as the vehicle was no longer covered under warranty, running over $5,000 in total cost. Other drivers have been plagued with transmission issues on this particular year, with gears slipping, requiring extensive rebuilds or a new transmission.

Both 2014 and 2015 share several complaints about the headlights of all systems. Owners describe their trouble with statements like, "You really notice how poor these lights are when the roads are wet. You can barely see the road in front of you." Another driver suggested that the headlights were so inept that a common household flashlight might provide better visibility of the road ahead. So many owners were dealing with issues while driving at night that GM was subjected to a class action lawsuit in 2015, alleging drivers and pedestrians were unsafe due to the poorly performing headlights.