The GMC Sierra draws 1.82 complaints per production run against 3.72 for the average car — better than typical. The worst model year is 1999 at 2.38 complaints per run; the best is 1989 at 1 — a 2.4-fold gap between two cars wearing the same badge. Failures cluster at 5 years, so only 22.3% of them fall inside the 3-year basic warranty.
Best and worst years
Ranked by complaints per production run rather than by raw count. A raw count only tells you which year sold well — the best-selling year always looks like the worst car. Dividing by the number of runs removes sales volume and leaves the fault rate.
| Model year | Per run | Complaints | Runs | Enough history? |
|---|---|---|---|---|
| 2008 | 419 | 244 | yes | |
| 2007 | 307 | 218 | yes | |
| 2006 | 246 | 176 | yes | |
| 2005 | 379 | 203 | yes | |
| 2004 | 477 | 242 | yes | |
| 2003 | 471 | 221 | yes | |
| 2002 | 508 | 265 | yes | |
| 2001 | 497 | 269 | yes | |
| 2000 | 572 | 252 | yes | |
| 1999 | 484 | 203 | yes | |
| 1998 | 206 | 145 | yes | |
| 1997 | 278 | 156 | yes | |
| 1996 | 205 | 131 | yes | |
| 1995 | 226 | 142 | yes | |
| 1994 | 174 | 126 | yes | |
| 1993 | 53 | 45 | yes | |
| 1992 | 22 | 21 | yes | |
| 1991 | 9 | 9 | yes | |
| 1990 | 16 | 16 | yes | |
| 1989 | 14 | 14 | yes |
Recent years are marked «too new» and left out of the ranking on purpose. Complaints accumulate for a decade after a car is sold, so a 2026 build will always look flawless next to a ten-year-old one. Comparing them would be dishonest. Among the 20 years with enough history, 1999 is the one to avoid and 1989 the one to look for.
When it starts to break
Not the calendar year the complaint was filed — the age of the car when it failed. This is the number that decides whether a fault costs you anything: inside the warranty the manufacturer pays, outside it you do.
| Age at failure | Complaints | Running total | Warranty |
|---|---|---|---|
| 0 years | 8.5% | covered | |
| 1 year | 14.8% | covered | |
| 2 years | 22.3% | covered | |
| 3 years | 32.4% | you pay | |
| 4 years | 42.5% | you pay | |
| 5 years | 51.1% | you pay | |
| 6 years | 57.7% | you pay | |
| 7 years | 64.8% | you pay | |
| 8 years | 73.7% | you pay | |
| 9 years | 81.7% | you pay | |
| 10 years | 87.7% | you pay | |
| 11 years | 91.9% | you pay | |
| 12 years | 95.1% | you pay | |
| 13 years | 97.2% | you pay | |
| 14 years | 98.9% | you pay | |
| 15 years | 100% | you pay |
Basic warranty on this car is 3 years / 36,000 miles. Only 22.3% of reported failures happen inside it — the remaining 77.7% come out of the owner's pocket. Powertrain cover (5 years / 60,000 miles) reaches further, but it only covers engine and transmission, and most complaints here are not either.
What actually fails
Systems by number of complaints, with the age at which each typically goes. The age column is the useful one — it tells you what to expect next on a car you already own, and what to inspect on one you are about to buy.
| System | Complaints | Typical age | Crash | Fire |
|---|---|---|---|---|
| Service Brakes | 6.8 yrs | 180 | 7 | |
| Hydraulic | 5 yrs | 130 | 6 | |
| Air Bags | 7.6 yrs | 119 | 2 | |
| Electrical System | 5 yrs | 3 | 49 | |
| Visibility | 5.2 yrs | 4 | 9 | |
| Steering | 4.1 yrs | 20 | 4 | |
| Power Train | 3.7 yrs | 18 | 7 | |
| Structure | 5.7 yrs | 14 | 1 |
What else in this class
Same vehicle class, so the comparison is fair — an estate against an estate, not against a coupé.
Good year or bad year — the VIN settles it.
- Check any VIN against complaints for its exact build year and plant
- Exact value for that car, adjusted for its mileage
- Full research report as a PDF you can hand to a mechanic
- Alerts if a recall lands on a car in your garage
- No ads, on every page
- No ads, no tracking — and much more
How we measure it
Reliability scores usually arrive as a number out of five with no working shown. We publish the arithmetic instead, because two things about it are arguable and you should be able to argue with them.
Rate, not total. A model that sold three million units collects more complaints than one that sold thirty thousand, and that says nothing about either. So we divide by the number of production runs — the distinct first-eleven-character VIN prefixes on record. Across 1,100,006 complaints and 295,326 runs the market average works out at 3.72 per run.
Age, not year. Every complaint carries an incident date and a model year, so we can work out how old the car was when it failed. That is what the warranty question turns on, and it is why our «worst year» rankings exclude anything built in the last 6 years — those cars simply have not had time to break yet.
What this is not. A complaint to NHTSA is a deliberate act, so this measures serious faults, not paint that scratched. It says nothing about running costs or how nice a car is to own. And an absence of complaints on a rare model means an absence of owners, not excellence.
Related tools
Frequently asked questions
Is the GMC Sierra reliable?
It draws 1.82 complaints per production run against 3.72 for the average car, so better than typical. Failures cluster around 5 years of age.
What are the best and worst years for the Sierra?
Worst is 1999 at 2.38 complaints per run; best is 1989 at 1. Years newer than 6 are excluded — they have not had time to accumulate complaints.
How long does a Sierra last?
Complaints reach their halfway point at 5 years. That is when faults start being reported in volume, not when the car stops — but it is the point at which ownership starts costing money.
Will the warranty cover it?
Basic cover is 3 years / 36,000 miles, and 22.3% of reported failures fall inside it. The rest are yours.
What fails most often?
Service Brakes with 2,156 complaints, typically at 6.8 years of age.