Truck maintenance statistics show the scale of inspection activity, the defects most often recorded by U.S. enforcement, and the workforce available to keep heavy vehicles operating. The figures below distinguish inspections from unique trucks, enforcement findings from confirmed failures, historical crash evidence from current conditions, and forecasts from observed results.
Key Truck Maintenance Statistics
The most useful high-level figures are:
- In 2023, 3,011,902 large-truck and bus inspections were conducted in the United States.
- In 2023, 1,994,946 vehicle inspections were recorded for large trucks and buses in the United States.
- In 2023, 22.6% of vehicle inspections had an out-of-service violation in the U.S. large-truck and bus inspection population.
- In 2023, 678,529 vehicle out-of-service violations were recorded in U.S. large-truck and bus inspections.
- In 2023, 336,623 citations for inoperable required lamps were recorded in U.S. vehicle inspections.
- In 2023, 125,372 violations for out-of-adjustment clamp- or roto-type brakes were recorded in U.S. vehicle inspections.
- In 2023, 103,511 violations for flat tires or audible tire air leaks were recorded in U.S. vehicle inspections.
- In 2023, 65,766 violations for tire tread below 2/32 inch in a major tread groove were recorded in U.S. vehicle inspections.
- In 2023, 839,638 Level I full inspections were conducted in the United States, with 231,130 receiving an out-of-service violation.
- In 2023, 1,057,511 Level II walk-around inspections were conducted in the United States, with 290,081 receiving an out-of-service violation.
- In 2023, 1,008,803 inspections involved carriers with 1–6 power units in the United States.
- In 2023, 2,461,709 inspections involved interstate operations in the United States, compared with 550,193 intrastate inspections.
- In 2023, 2,367,725 inspections involved vehicles above 26,000 pounds GCWR in the United States.
- From April 2001 through December 2003, vehicle loss of control was the critical event for 29% of large trucks in the U.S. LTCCS sample.
- From April 2001 through December 2003, vehicle factors were the critical reason for 10% of coded large trucks in the LTCCS analysis.
- In 2025, about 242,400 heavy vehicle and mobile equipment service technician jobs existed in the United States.
- In May 2025, the median annual wage was $63,850 for U.S. heavy vehicle and mobile equipment service technicians.
- From 2025 to 2035, BLS projects 17,100 additional jobs in the broad U.S. heavy vehicle and mobile equipment service technician occupation.
Contents
- Inspection volume and enforcement trends
- Inspection types and out-of-service rates
- Common maintenance violations
- Fleet size, operation and vehicle weight
- Crash-causation and maintenance evidence
- Maintenance workforce and outlook
Truck Maintenance Inspection Volume and Enforcement Trends
The Federal Motor Carrier Safety Administration’s 2024 Pocket Guide reports MCMIS inspection data with a snapshot date of January 26, 2024. The population is large trucks and buses unless a measure is specifically described otherwise, so these numbers are enforcement activity rather than a direct count of truck maintenance events.
| Year | Large-truck and bus inspections | Vehicle OOS rate |
|---|---|---|
| 2019 | 3,471,201 | 20.6% |
| 2020 | 2,582,347 | 20.7% |
| 2021 | 2,881,886 | 21.4% |
| 2022 | 2,991,426 | 22.6% |
| 2023 | 3,011,902 | 22.6% |
Source: 2024 Pocket Guide to Large Truck and Bus Statistics.
In 2023, state inspectors conducted 2,936,144 inspections and federal inspectors conducted 75,758. FMCSA listed 13,564 safety inspectors, including 13,096 state and 468 federal inspectors; the agency notes that not all listed personnel were assigned full-time to inspections.
Vehicle inspections totaled 1,994,946 in 2023 and produced 3,097,660 vehicle violations. Because a violation count is not a count of unique vehicles, the total should not be read as a fleet-wide failure rate.
Traffic-enforcement inspections totaled 593,547, including 226,846 vehicle-observed traffic-enforcement inspections. The latter produced 520,406 vehicle-observed traffic-enforcement violations, and one inspection may produce multiple violations.
Truck Maintenance Inspection Types and Out-of-Service Rates
The 2023 vehicle out-of-service result was 22.6%, with 450,477 of 1,994,946 vehicle inspections receiving an OOS violation. This is an enforcement finding for a combined large-truck and bus population, not confirmation that 22.6% of the entire U.S. truck fleet was mechanically unsafe.
| Inspection type | 2023 inspections | Inspections with OOS violation |
|---|---|---|
| Level I full | 839,638 | 231,130 |
| Level II walk-around | 1,057,511 | 290,081 |
| Level III driver-only | 1,011,089 | 63,801 |
| Level V terminal | 96,326 | 4,728 |
| Level VI radioactive-material | 1,471 | 5 |
Source: 2024 Pocket Guide to Large Truck and Bus Statistics. Level III is driver-only activity, while Level VI is a small specialized population.
For comparison, the 2023 driver OOS rate was 6.4%, with 185,640 of 2,909,709 driver inspections receiving an OOS violation. The hazardous-material inspection OOS rate was 4.0%, with 6,992 of 174,620 inspections receiving an OOS violation; neither figure is a vehicle-maintenance measure.
Most Common Truck Maintenance Violations: Brakes, Tires and Lighting
FMCSA’s 2023 top-20 vehicle-violation table shows which maintenance-related findings appeared most often in inspected vehicles. These are citations or violations, not necessarily unique trucks, and the table does not represent every violation category.
- Inoperable required lamps generated 336,623 citations, the largest listed vehicle-violation category.
- Operating without proof of a periodic inspection generated 190,975 violations; this is a documentation and compliance finding rather than a physical-condition measure.
- Out-of-adjustment clamp- or roto-type brakes generated 125,372 violations.
- Flat tires or audible tire air leaks generated 103,511 violations.
- Inoperative or defective windshield wipers generated 82,983 violations.
- Defective lighting devices or reflective material generated 79,054 violations.
- Automatic air-brake adjustment systems that failed to compensate for wear generated 69,882 violations. The cited code applies to commercial motor vehicles manufactured after October 19, 1994.
- Inspection, repair and maintenance of parts and accessories was cited 68,964 times under a broad all-other-vehicle-defects category.
- Tire tread below 2/32 inch in a major tread groove generated 65,766 violations.
- Oil or grease leaks generated 54,481 vehicle violations.
- Brakes classified out of service when defective brakes reached at least 20% of service brakes produced 54,150 violations. The 20% threshold is an inspection definition, not a fleet failure rate.
- Inoperative or defective brakes generated 53,041 violations.
- A missing or defective trailer ABS malfunction-indicator lamp generated 49,156 violations for applicable trailers manufactured after March 1, 1998.
- Inoperative brake lamps generated 45,959 violations.
- Brake-hose or tubing chafing or kinking generated 41,973 violations.
Source: 2024 Pocket Guide to Large Truck and Bus Statistics.
The pattern puts lighting, brake adjustment, tires, visibility equipment, leaks and inspection documentation in the same enforcement picture. It should not be converted into a ranking of repair costs or a probability that an individual truck will fail.
Truck Maintenance Data by Fleet Size, Operation and Vehicle Weight
Inspection counts also show how enforcement activity was distributed across carrier and vehicle groups in 2023. These are counts of inspections, not normalized rates by fleet population, vehicle miles or number of carriers.
| Group | 2023 inspections |
|---|---|
| Carriers with 1–6 power units | 1,008,803 |
| Carriers with 7–20 power units | 496,483 |
| Carriers with 21–100 power units | 600,924 |
| Carriers with more than 100 power units | 817,289 |
Source: 2024 Pocket Guide to Large Truck and Bus Statistics.
Very small carriers with 1–6 power units accounted for the largest listed fleet-size inspection count, while large carriers with more than 100 power units accounted for 817,289. The figures cannot establish that one fleet-size group has better or worse maintenance performance without denominators.
Interstate operations accounted for 2,461,709 inspections, compared with 550,193 intrastate inspections. By gross combination weight rating, vehicles above 26,000 pounds accounted for 2,367,725 inspections, those from 10,000 to 26,000 pounds accounted for 538,191, and those below 10,000 pounds accounted for 8,934.
Truck Maintenance, Breakdowns and Crash-Causation Evidence
The Large Truck Crash Causation Study examined serious U.S. crashes from April 2001 through December 2003. Its sample contained 963 serious crashes involving 1,123 large trucks, 959 other motor vehicles, 249 fatalities and 1,654 injuries; the study covered large trucks over 10,000-pound GVWR.
In the LTCCS sample, vehicle loss of control was the critical event for 29% of large trucks. That category included vehicle systems failure along with speed, cargo shift and road conditions, so it is not a maintenance-only measure.
The analysis assigned a critical reason to 55% of large trucks involved in all sampled crash types. Vehicle factors were the critical reason for 10% of the 78,000 coded large trucks in the analysis table, but vehicle factors included maintenance status and other vehicle conditions.
In two-vehicle crashes involving one truck and one passenger vehicle, 44% of large trucks were assigned the critical reason. These results are weighted crash-analysis estimates from a serious-crash study, not current maintenance prevalence and not proof that maintenance caused a crash.
Source: The Large Truck Crash Causation Study – Analysis Brief.
Truck Maintenance Workforce Statistics and Outlook
The Bureau of Labor Statistics provides workforce context through the broader heavy vehicle and mobile equipment service technician occupation, which includes more than road-truck maintenance. In 2025, BLS counted about 242,400 jobs in the occupation, including 180,300 mobile heavy equipment mechanic jobs, except engines.
| Workforce measure | U.S. figure | Period |
|---|---|---|
| Heavy vehicle and mobile equipment service technician jobs | 242,400 | 2025 |
| Mobile heavy equipment mechanics, except engines | 180,300 | 2025 |
| Median annual wage | $63,850 | May 2025 |
| Below the 10th-percentile threshold | Less than $45,460 | May 2025 |
| Above the 90th-percentile threshold | More than $93,450 | May 2025 |
Source: Heavy Vehicle and Mobile Equipment Service Technicians: Occupational Outlook Handbook.
BLS projects the broad occupation to grow from 242,400 jobs in 2025 to 259,500 in 2035, a 7% increase and 17,100 additional jobs. It also projects about 20,300 openings per year over 2025–2035, including replacement demand and growth across the occupation.
These labor figures help describe repair capacity, but they are not truck-only employment, truck-maintenance spending or a measure of technician shortages. The source’s occupational scope includes heavy vehicles and mobile equipment across several industries.