Career Guide
How to Become a Diesel Mechanic
A diesel mechanic, which BLS calls a diesel service technician, inspects, repairs and overhauls buses, trucks and other vehicles with diesel engines. Most learn on the job after high school, and employers may prefer candidates with postsecondary diesel training. BLS reports a May 2025 median of $61,770 a year.
By Trevor Rupe, Contributor at Savo Media Group
At a Glance
- $61,770 median annual pay for bus and truck mechanics and diesel engine specialists, BLS May 2025; the middle 80 percent earned $44,530 to $88,740.
- 289,960 wage and salary jobs in the occupation.
- High school diploma or equivalent is the typical entry education BLS lists, with long-term on-the-job training.
- 4% growth projected for 2025 to 2035, with about 24,400 openings a year.
What a Diesel Mechanic Does
BLS describes diesel service technicians and mechanics as workers who inspect, repair or overhaul buses and trucks, or maintain and repair any type of diesel engine. The work covers brake systems, steering, transmissions and engines, followed by repair or replacement of whatever is malfunctioning.
Technicians read and interpret diagnostic test results, follow checklists so that every critical part is examined, and document the repair and the parts used. Diesel technicians make engine repairs on a variety of vehicles, including trucks, bulldozers, commercial boats and passenger vehicles, and they work on electrical and exhaust systems so that vehicles comply with pollution regulations.
Many shops use computer diagnostic equipment to find problems and adjust engine functions, alongside power and machine tools such as pneumatic wrenches, lathes, grinding machines and welding equipment.
- Inspect and test brakes, steering, transmissions and engines
- Interpret diagnostic results to find the mechanical problem
- Repair or replace malfunctioning mechanical and electrical parts
- Retrofit engines with emission control systems where regulations require it
Work Environment
BLS says diesel technicians usually work in well-ventilated and sometimes noisy repair shops and occasionally repair vehicles on roadsides or at worksites. They often lift heavy parts and tools, handle greasy or dirty equipment and work in uncomfortable positions, and sprains and cuts are common.
Most diesel technicians work full time, and some work more than 40 hours per week.
Training Paths
How to become a diesel mechanic depends on the route a person takes, and this section sets out the training the Bureau of Labor Statistics describes.
BLS says most diesel technicians learn on the job after high school, and that those who start without postsecondary education are trained extensively at work. Employers may prefer candidates who completed a postsecondary program in diesel engine repair, and some community colleges and vocational-technical schools offer certificate or degree programs.
The training this site ranks is the ASE Education Foundation accredited Medium/Heavy Duty Truck program, the kind of certificate and degree program BLS says community colleges and vocational-technical schools offer. The ranking also has a separate list of the programs that award an associate degree.
Accredited Programs That Train for This Job
The school route to this job runs through accredited programs, and these ranked lists compare them.
ASE Certification for Diesel Mechanics
ASE certifies individual technicians in its medium-heavy truck series, tests T1 through T8, which include a diesel engines test (T2), drive train, brakes, suspension and steering, electrical systems, HVAC and preventive maintenance inspection. A technician certified in T2 through T8 is recognized as an ASE Certified Master Medium-Heavy Truck Technician.
Like the automobile tests, the T-series requires two years of full-time hands-on experience, or the part-time equivalent, plus a passing test score. ASE credits completion of an ASE-accredited Medium/Heavy Truck program as one year of that experience. Master status has to be kept current: certifications are valid for five years.
BLS says employers may require or prefer certified diesel technicians and that certification may bring higher pay. It also notes that diesel technicians might need a commercial driver license to test-drive buses and large trucks.
Diesel Mechanic Pay
BLS reports a May 2025 median of $61,770 a year for bus and truck mechanics and diesel engine specialists (SOC 49-3031). The lowest-paid tenth earned under $44,530 and the highest-paid tenth over $88,740. Percentiles are points in the wage distribution, not stages of a career, and OEWS counts wage and salary jobs only.
| Measure | Figure |
|---|---|
| Median annual wage | $61,770 |
| Mean annual wage | $64,320 |
| 10th percentile | $44,530 |
| 25th percentile | $50,540 |
| 75th percentile | $75,470 |
| 90th percentile | $88,740 |
| Median hourly wage | $29.70 |
| Wage and salary jobs | 289,960 |
Among states with at least 500 jobs in the occupation, the highest medians are in Hawaii ($80,080) , Washington ($77,900) , and Alaska ($75,580) .
The diesel mechanic salary page has the full state and metro tables, and the salary hub compares all five trades.
Job Outlook
BLS projects employment of diesel service technicians and mechanics to grow 4 percent from 2025 to 2035, about as fast as the average for all occupations, with about 24,400 openings a year. BLS also cautions that 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.
Questions About How to Become a Diesel Mechanic
How long is diesel mechanic school?
BLS says some community colleges and vocational-technical schools offer certificate or degree programs in diesel engine repair. It lists a high school diploma or equivalent as the typical entry education, with long-term on-the-job training, and says employers may prefer candidates who completed a postsecondary diesel program. The diesel ranking and its associate degree list cover the accredited programs.
Do diesel mechanics need a CDL?
BLS says diesel technicians might need a commercial driver license to test-drive buses and large trucks. It does not list it as a requirement of the occupation.
How much do diesel mechanics make?
BLS reports a May 2025 median of $61,770 a year for bus and truck mechanics and diesel engine specialists (SOC 49-3031), with the lowest-paid tenth earning under $44,530 and the highest-paid tenth over $88,740. That is $11,150 above the May 2025 median for automotive service technicians. State figures are on the diesel mechanic salary page.
Is ASE certification required for diesel mechanics?
BLS says employers may require or prefer certification, not that it is required by law. ASE certification takes a passing test and two years of hands-on experience, of which completing an ASE-accredited Medium/Heavy Truck program counts for one.
Sources for Diesel Mechanic Career Facts
- BLS Occupational Outlook Handbook, Diesel Service Technicians and Mechanics 2025-35 edition, read October 23, 2026.
- ASE, Medium-Heavy Truck Tests (T1-T8) Read October 23, 2026.
- ASE, Work Experience Form Instructions (training credit) Training credit toward experience; read October 23, 2026.
- ASE, Frequently Asked Questions Read October 23, 2026.
- Bureau of Labor Statistics, Occupational Employment and Wage Statistics, Bus and Truck Mechanics and Diesel Engine Specialists May 2025 estimates, SOC 49-3031, read October 23, 2026.
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