Diesel Service Technicians and Mechanics

Summary

What Diesel Service Technicians and Mechanics Do About this section

Diesel service technicians and mechanics may work on a vehicle’s electrical system, make major engine repairs, or retrofit engines with emission control systems to comply with pollution regulations.

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.

Duties

Diesel service technicians and mechanics typically do the following:

• Inspect and test brake systems, steering mechanisms, transmissions, engines, and other parts of vehicles
• Read and interpret diagnostic test results to identify mechanical problems
• Follow checklists to ensure that all critical parts are examined
• Repair or replace malfunctioning parts and other mechanical or electrical equipment
• Perform basic care and maintenance, including changing oil, checking fluid levels, and rotating tires
• Document repairs and maintenance performed, including parts used, hours worked, and vehicle condition
• Explain problems and repairs to clients 

Diesel technicians make engine repairs on a variety of vehicles, including trucks, bulldozers, commercial boats, and passenger vehicles. They also work on a vehicle’s electrical and exhaust systems to comply with pollution regulations.

In many shops, workers use computer diagnostic equipment to detect 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 are commonly used, including pliers, sockets and ratchets, and screwdrivers.

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.

Work Environment About this section

Diesel technicians usually work in well-ventilated and sometimes noisy repair shops.

Diesel service technicians and mechanics held about 316,000 jobs in 2025. Some of the largest employers of diesel service technicians and mechanics were as follows:

Diesel technicians usually work in well-ventilated and sometimes noisy repair shops. They occasionally repair vehicles on roadsides or at worksites.

Injuries and Illnesses

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.

Work Schedules

Most diesel technicians work full time, and some work more than 40 hours per week. Some 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.

How to Become a Diesel Service Technician or Mechanic About this section

Diesel technicians initially learn to perform routine maintenance and repair tasks.

Although most diesel technicians learn on the job after a high school education, employers may prefer to hire candidates who have completed postsecondary training programs in diesel engine repair. In addition, industry certification may be required.

Education

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 may prefer to hire candidates with postsecondary education in diesel engine repair. Some community colleges and vocational-technical schools offer certificate or degree programs in diesel engine repair.

These 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.

Training

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.

Over the course of their careers, diesel technicians must learn to use new techniques and equipment. Employers may send experienced technicians to special training classes conducted by manufacturers and vendors to learn about the latest diesel technology.

Licenses, Certifications, and Registrations

Employers may require or prefer that their diesel technicians become certified. Having industry certifications demonstrates competence and may bring higher pay.

To become certified, diesel technicians may need previous experience and must pass an exam. Information on certifications is available from CareerOneStop.

Diesel technicians might need a commercial driver’s license to test-drive buses and large trucks.

Important Qualities

The following are examples of qualities that are important for these workers to perform their duties. For more information, visit the Employment Projections (EP) skills data page.

Customer-service skills. Diesel technicians discuss problems and necessary repairs with their customers. They must be courteous, listen well, and be 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 may be 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 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.

Problem-solving skills. Diesel technicians must be able to diagnose problems with diesel engines and systems to determine the best way to repair them.

Pay About this section

The median annual wage for diesel service technicians and mechanics was $61,770 in May 2025. 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 $44,530, and the highest 10 percent earned more than $88,740.

In May 2025, the median annual wages for diesel service technicians and mechanics in some of the top industries in which they worked were as follows:

Most diesel technicians work full time, and some work more than 40 hours per week. Some 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.

Job Outlook About this section

Employment of diesel service technicians and mechanics is projected to grow 4 percent from 2025 to 2035, about as fast as the average for all occupations.

About 24,400 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.

Employment

As more freight is shipped across the country, diesel-powered trucks will continue to be needed to carry freight wherever trains and pipelines are neither available nor economical. In addition, aging vehicles with diesel engines are likely to require more maintenance and repair, supporting the need for diesel technicians.

However, some demand for these workers may be reduced as more firms turn away from diesel-powered trucks and vehicles in favor of those that require less maintenance and repair. For example, trucks used for courier and delivery services, such as package delivery, are expected to increasingly be electric.

State & Area Data About this section

Occupational Employment and Wage Statistics (OEWS)

The Occupational Employment and Wage Statistics (OEWS) program produces employment and wage estimates annually for over 800 occupations. These estimates are available for the nation as a whole, for individual states, and for metropolitan and nonmetropolitan areas. The link below goes to OEWS data maps for employment and wages by state and area. Use the dropdown boxes to select an occupation.

• Occupational Employment and Wage Statistics (OEWS) Profiles

Projections Central

Occupational employment projections are developed for all states by Labor Market Information (LMI) or individual state Employment Projections offices. All state projections data are available at https://projectionscentral.org. Information on this site allows projected employment growth for an occupation to be compared among states or to be compared within one state. In addition, states may produce projections for areas; there are links to each state’s websites where these data may be retrieved.

CareerOneStop

CareerOneStop includes hundreds of occupational profiles with data available by state and metro area. There are links in the left-hand side menu to compare occupational employment by state and occupational wages by local area or metro area. There is also a salary info tool to search for wages by zip code.

Contacts for More Information About this section

For information about certifications, visit CareerOneStop.

O*NET

Bus and Truck Mechanics and Diesel Engine Specialists