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Mechanics, Maintenance & Manufacturing career
Diesel Mechanic
Also called: Diesel Technician · Heavy-Duty Truck Mechanic · Fleet Mechanic · Diesel Engine Specialist
What diesel mechanics do, what they earn, how long training takes and how to get started, with official BLS pay data and practical, job-level detail.
What does a diesel mechanic do?
Diesel mechanics inspect, diagnose, maintain and repair diesel engines and the trucks, buses and equipment they power, from engines and air brakes to electronics and emissions systems. The median pay is $61,770 per year (BLS, May 2025), most people train for about 6–24 months, and employment is projected to grow +3.6% from 2025–35.
Pay data: BLS OEWS, May 2025 · Outlook: BLS 2025–35 · Checked October 15, 2026
- Median pay$61,770$29.70/hour · May 2025
- Job growth+3.6%2025–35, about as fast as average
- Openings per year24,400Average, 2025–35
- Typical entry educationHigh school diploma or equivalentBLS classification
- Time to train6–24 monthsTypical program length
- U.S. jobs316,000Employment, 2025
What diesel mechanics do
Diesel mechanics keep freight, transit and construction moving. They perform preventive maintenance, diagnose problems with computer software, repair engines, transmissions, air brakes, suspensions, electrical systems and modern emissions equipment such as diesel particulate filters and selective catalytic reduction.
Many diesel techs start with a postsecondary program of six months to two years; others learn on the job. ASE certifications for medium-heavy trucks build credibility and pay, and techs who master electronics and emissions systems are in particular demand.
Typical duties
- Perform preventive maintenance inspections and services
- Diagnose problems using diagnostic software and test equipment
- Repair or rebuild engines, transmissions and drivetrains
- Inspect and repair air brakes, steering and suspension
- Service aftertreatment systems such as DPF, DEF and SCR
- Repair electrical systems and replace sensors and modules
- Document work on repair orders and inspection reports
Work environment and schedule
Diesel mechanics work in fleet shops, dealerships, independent repair shops and on the road as field service techs. Work can be dirty, loud and physically demanding, sometimes outdoors in roadside repairs.
Schedule: Usually full-time; many shops run evening and overnight shifts so trucks are ready by morning. Overtime is common.
A day in the life
- Review work orders: two PM services, a check-engine light and a brake complaint.
- Perform a PM: change oil and filters, grease the chassis and inspect belts, hoses and lights.
- Connect diagnostic software to a truck with an aftertreatment fault and run a parked regeneration.
- Measure air brake pushrod stroke and adjust a slack adjuster out of spec.
See a full day in the life of a diesel mechanic →
Diesel Mechanic salary
Half of diesel mechanics earned more than $61,770 and half earned less in May 2025. Pay ranged from about $44,530 for the lowest 10% to $88,740 for the top 10%.
Full diesel mechanic pay scale and hourly rates →
How to become a diesel mechanic
- Finish high school
- Complete diesel technology training
- Start as an entry-level tech
- Earn ASE certifications
- Specialize
A high school diploma is typical. Many diesel techs complete a six-month to two-year program at a technical school or community college; others start as lube techs and learn on the job.
Step-by-step guide to becoming a diesel mechanic →
Skills and tools
Technical skills
- Diesel engine diagnostics
- Air brake systems
- Electrical and electronic troubleshooting
- Aftertreatment (DPF, DEF, SCR)
- Preventive maintenance inspections
People skills
- Problem-solving
- Attention to detail
- Time management
- Communication with drivers and service writers
All diesel mechanic skills and tools →
Pros and cons
Pros
- Strong demand from trucking and fleets
- Good pay with overtime and certifications
- Problem-solving with modern diagnostics
- Many employers pay for training and tools
Cons
- Physically demanding and dirty work
- Tools can be a significant personal investment
- Night or weekend shifts at some shops
- Constant learning as emissions and electronics change
Certifications and licenses
- ASE Medium-Heavy Truck (T-series): Certifications covering diesel engines, drivetrains, brakes, suspension, electrical and more.
- DOT annual inspector qualification: Required to perform federal periodic inspections on commercial vehicles.
- Manufacturer certifications: Training from engine and truck makers such as Cummins, Detroit or Freightliner.
- CDL: Helpful for road-testing and moving trucks.
Career path
- Lube Tech or Apprentice: Perform services and learn systems.
- Diesel Technician: Diagnose and repair trucks and equipment.
- Master or Lead Technician: Handle complex diagnostics and mentor others.
- Shop Foreman or Fleet Manager: Run maintenance operations.
Learn the job before day one
Our Diesel Mechanic training (10 hours, $89.99) covers the role, 15+ key terms, step-by-step procedures such as perform a truck PM service and check air brake pushrod stroke, safety and how to land your first job.
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Compare: Diesel Mechanic vs. Auto Technician · Diesel Mechanic vs. Truck Driver · Diesel Mechanic vs. Heavy Equipment Operator · Diesel Mechanic vs. Maintenance Technician
Diesel Mechanic FAQ
How long does it take to become a diesel mechanic?
Technical programs take six months to two years. Many techs also learn on the job and earn ASE certifications after gaining experience.
Do diesel mechanics need certification?
Not legally in most cases, but ASE certifications and manufacturer training raise pay and opportunities.
Do diesel mechanics have to buy their own tools?
Many do, especially hand tools. Some employers provide allowances or specialty tools.
How much does a diesel mechanic make?
The median annual wage for diesel mechanics was $61,770 ($29.70 per hour) in May 2025, according to the U.S. Bureau of Labor Statistics. The lowest 10% earned less than $44,530 and the highest 10% earned more than $88,740.
How long does it take to become a diesel mechanic?
Most people need about 6–24 months of training. A high school diploma is typical. Many diesel techs complete a six-month to two-year program at a technical school or community college; others start as lube techs and learn on the job.
Do you need a degree to be a diesel mechanic?
No four-year degree is typically required. BLS lists “high school diploma or equivalent” as the typical entry-level education, plus long-term on-the-job training.
More diesel mechanic questions →
Sources
- U.S. Bureau of Labor Statistics, BLS Occupational Employment and Wage Statistics (OEWS), May 2025, SOC 49-3031 (Bus and truck mechanics and diesel engine specialists).
- U.S. Bureau of Labor Statistics, BLS Employment Projections, Table 1.2 (2025–35).
- O*NET OnLine summary for Bus and truck mechanics and diesel engine specialists (U.S. Department of Labor).
- BLS Occupational Outlook Handbook.
Reviewed by the Career Education Institute Curriculum Team. Pay figures are national estimates; local pay varies. See our editorial policy.