596 problems have been reported for the 2021 GMC Sierra 1500. The following chart shows the 22 most common problems for 2021 GMC Sierra 1500. The number one most common problem is related to the vehicle's engine and engine cooling with 261 problems. The second most common problem is related to the vehicle's power train (104 problems).
In our research we use the PPMY index to compare the reliability of vehicles. The PPMY index of a certain model is defined as the problems reported per thousand vehicles per Year. The total sales of the 2021 GMC Sierra 1500 in the United States are 151,404 units [1]. If the total number of problems reported by GMC Sierra 1500 owners in the last 5 years is 596, and the age of the vehicle is 5, the PPMY index can then be calculated as
PPMY Index = 596 / 151,404 / 5 * 1000 = 0.79.
For more information, refer to this page: A study of reliability comparison across GMC Sierra 1500 model year vehicles.
The following chart shows the number of problems reported during each of the service years since the debut of the 2021 GMC Sierra 1500 in 2021.
| Service Year | Number of Problems |
|---|---|
| 2026 | |
| 2025 | |
| 2024 | |
| 2023 | |
| 2022 | |
| 2021 |
When making the decision between buying a new or used GMC Sierra 1500, the following table can be used to compare the 2021 GMC Sierra 1500 with the GMC Sierra 1500 from other model years. Note that the number of problems reported for the 2021 Sierra 1500 is 596 while the average number of problems reported for the 31 model years of the GMC Sierra 1500 is 330.