Diesel service technicians and mechanics (also known as diesel technicians) inspect, repair, or overhaul buses and trucks, or maintain and repair any type of diesel engine.
Diesel service technicians and mechanics typically do the following:
Because of their efficiency and durability, diesel engines have become the standard in powering trucks and buses. Other heavy vehicles and mobile equipment, including bulldozers and cranes, also are powered by diesel engines, as are many commercial boats and some passenger vehicles and pickups.
Diesel technicians make major and minor engine repairs, and work on a vehicle’s electrical and exhaust systems to comply with pollution regulations.
Diesel engine maintenance and repair is becoming more complex as engines and other components use more electronic systems to control their operation. For example, fuel injection and engine timing systems rely on microprocessors to maximize fuel efficiency and minimize harmful emissions. In most shops, workers often use hand-held or laptop computers to diagnose problems and adjust engine functions.
Diesel technicians also use a variety of power and machine tools, such as pneumatic wrenches, lathes, grinding machines, and welding equipment. Hand tools, including pliers, sockets and ratchets, and screwdrivers, are commonly used.
Employers typically provide expensive power tools and computerized equipment, but workers generally acquire their own hand tools over time.
Technicians and mechanics who work primarily on automobiles are described in the profile on automotive service technicians and mechanics.
Technicians and mechanics who work primarily on farm equipment, construction vehicles, and railcars, are described in the profile on heavy vehicle and mobile equipment service technicians.
Technicians and mechanics who work primarily on motorboats, motorcycles, and small all-terrain vehicles are described in the small engine mechanics profile.
Diesel service technicians and mechanics held about 293,200 jobs in 2021. The largest employers of diesel service technicians and mechanics were as follows:
| Truck transportation | 20% |
| Wholesale trade | 13 |
| Local government, excluding education and hospitals | 9 |
| Automotive repair and maintenance | 8 |
| Self-employed workers | 8 |
Diesel technicians usually work in well-ventilated and sometimes noisy repair shops. They occasionally repair vehicles on roadsides or at worksites.
Diesel service technicians and mechanics often lift heavy parts and tools, handle greasy or dirty equipment, and work in uncomfortable positions. Sprains and cuts are common among these workers. Diesel technicians need to follow some safety precautions when in the workplace.
Most diesel technicians work full time. Overtime is common, as many repair shops extend their service hours during evenings and weekends. In addition, some truck and bus repair shops provide 24-hour maintenance and repair services.
Although most diesel technicians learn on the job after a high school education, employers are increasingly preferring applicants who have completed postsecondary training programs in diesel engine repair. In addition, obtaining industry certification may be helpful because certification demonstrates a diesel technician’s competence and experience.
Most employers require a high school diploma or equivalent. High school or postsecondary courses in automotive repair, electronics, and mathematics provide a strong educational background for a career as a diesel technician.
Some employers prefer to hire workers with postsecondary education in diesel engine repair. Many community colleges and trade and vocational schools offer certificate or degree programs in diesel engine repair.
These degree programs mix classroom instruction with hands-on training and include learning the basics of diesel technology, repair techniques and equipment, and practical exercises. Students also learn how to interpret technical manuals and electronic diagnostic reports.
Diesel technicians who begin working without any postsecondary education are trained extensively on the job. Trainees are assigned basic tasks, such as cleaning parts, checking fuel and oil levels, and driving vehicles in and out of the shop.
After they learn routine maintenance and repair tasks and demonstrate competence, trainees move on to more complicated subjects, such as vehicle diagnostics. This process can take from 3 to 4 years, at which point a trainee is usually considered a journey-level diesel technician.
Over the course of their careers, diesel technicians must learn to use new techniques and equipment. Employers often send experienced technicians to special training classes conducted by manufacturers and vendors to learn about the latest diesel technology.
Certification from the National Institute for Automotive Service Excellence (ASE) is the standard credential for diesel and other automotive service technicians and mechanics. Although not required, this certification demonstrates a diesel technician’s competence and experience to potential employers and clients, and often brings higher pay.
Diesel technicians may be certified in specific repair areas, such as drivetrains, electronic systems, and preventative maintenance and inspection. To earn certification, technicians must have 2 years of work experience and pass one or more ASE exams. To remain certified, diesel technicians must pass a recertification exam every 5 years.
Many diesel technicians are required to have a commercial driver’s license so that they may test-drive buses and large trucks.
Customer-service skills. Diesel technicians frequently discuss automotive problems and necessary repairs with their customers. They must be courteous, good listeners, and ready to answer customers’ questions.
Detail oriented. Diesel technicians must be aware of small details when inspecting or repairing engines and components, because mechanical and electronic malfunctions are often due to misalignments and other easy-to-miss causes.
Dexterity. Mechanics need a steady hand and good hand–eye coordination for many tasks, such as disassembling engine parts, connecting or attaching components, and using hand tools.
Mechanical skills. Diesel technicians must be familiar with engine components and systems and know how they interact with each other. They often disassemble major parts for repairs, and they must be able to put them back together properly.
Organizational skills. Diesel technicians must keep workspaces clean and organized in order to maintain safety and accountability for parts.
Physical strength. Diesel technicians often lift heavy parts and tools, such as exhaust system components and pneumatic wrenches.
Troubleshooting skills. Diesel technicians use diagnostic equipment on engine systems and components in order to identify and fix problems in mechanical and electronic systems. They must be familiar with electronic control systems and the appropriate tools needed to fix and maintain them.
Median annual wages, May 2021
The median annual wage for diesel service technicians and mechanics was $48,690 in May 2021. The median wage is the wage at which half the workers in an occupation earned more than that amount and half earned less. The lowest 10 percent earned less than $35,730, and the highest 10 percent earned more than $76,150.
In May 2021, the median annual wages for diesel service technicians and mechanics in the top industries in which they worked were as follows:
| Local government, excluding education and hospitals | $60,670 |
| Wholesale trade | 55,940 |
| Automotive repair and maintenance | 47,630 |
| Truck transportation | 47,120 |
Many diesel technicians, especially those employed by truck fleet dealers and repair shops, receive a commission in addition to their base salary.
Most diesel technicians work full time. Overtime is common, as many repair shops extend their service hours during evenings and weekends. In addition, some truck and bus repair shops provide 24-hour maintenance and repair services.
Percent change in employment, projected 2021-31
Employment of diesel service technicians and mechanics is projected to grow 4 percent from 2021 to 2031, about as fast as the average for all occupations.
About 28,500 openings for diesel service technicians and mechanics are projected each year, on average, over the decade. Many of those openings are expected to result from the need to replace workers who transfer to different occupations or exit the labor force, such as to retire.
As more freight is shipped across the country, additional diesel-powered trucks will be needed to carry freight wherever trains and pipelines are not available or economical. In addition, aging vehicles with diesel engines are likely to require more maintenance and repair, supporting the need for diesel technicians.
| Occupational Title | SOC Code | Employment, 2021 | Projected Employment, 2031 | Change, 2021-31 | Employment by Industry | ||
|---|---|---|---|---|---|---|---|
| Percent | Numeric | ||||||
SOURCE: U.S. Bureau of Labor Statistics, Employment Projections program |
|||||||
Bus and truck mechanics and diesel engine specialists |
49-3031 | 293,200 | 305,800 | 4 | 12,600 | Get data | |
For more information about careers and education for diesel service technicians and mechanics, visit
Association of Diesel Specialists
National Automotive Technicians Education Foundation
For more information about certification, visit
National Institute for Automotive Service Excellence