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Diesel Mechanic Certifications

Feb 23, 2022 ·

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Industries worldwide rely on the power of diesel technology to operate their commercial vehicles and heavy-equipment systems. Those with a passion for powerful diesel engines can pursue careers as diesel mechanics, also known as diesel technicians, and work hands-on with these systems.

Having the right training under your belt is necessary and, in most cases, preferred when entering the workforce. Universal Technical Institute’s Diesel Technology program can help give you the hands-on experience and training employers are looking for. And if you want to take your education even further, the next step would be to look into obtaining diesel mechanic certifications.

Keep reading to learn more about how to become a certified diesel mechanic.

What Are Diesel Mechanic Certifications?

Diesel technician certifications are documents that show that someone has demonstrated the required knowledge in specified areas. While you can work in the industry without having certifications, they can help improve your outlook when it comes to employment and salary.

One of the top groups certifying mechanics is the National Institute for Automotive Service Excellence, or ASE. Since 1972, they have been offering a wide range of certification tests for automotive and diesel technicians that build upon the foundational education that can be received at trade schools like Universal Technical Institute (UTI).

Benefits to getting certified include recognition and respect in the industry that can help technicians with job searches or with advancing their careers.1 Those who need repairs or maintenance for their diesel machinery know they can count on an ASE-certified technician to get the job done right.

Preparing for Certification Tests

It’s important to take the time to prepare well for taking certification tests. Receiving core diesel training at a school accredited by the ASE Education Foundation can provide you with a great starting point.

UTI’s Diesel Technology program trains students how to diagnose and repair diesel engines as well as medium/heavy-duty chassis subsystems in as little as 45 weeks7 and is offered at campuses nationwide. Students also have the option to further their education with specialized training programs that give them in-depth experience working with big names in the industry like Cummins, Peterbilt, Freightliner and Fendt.15

Certification also requires proof of working in the industry or relevant training. Graduates of the Diesel program at UTI can substitute the training they received for one of the two years of work experience that are required to become ASE certified.16

When it comes to test prep and training, the ASE website has several resources that can help you feel confident when the time comes:

  • Practice tests: These online tests help familiarize you with ASE-style tests before jumping into the real thing. Feedback is also provided with a performance report that provides explanations for correct and incorrect answers.
  • Study guides: Study guides are available for each test series and help provide more details on individual tests within the series, such as the major content areas and the amount of time given to complete a test. Sample questions are also provided.
  • Testing demo: A free testing demo lets you get a sense of what an actual test is like within the ASE testing platform and explains the functions and features within the system.

By utilizing these resources and by drawing on the knowledge you already have from completing a diesel training program, you can feel more prepared to take certification tests.

Types of Diesel Certification Tests

ASE offers several medium/heavy truck tests that cover the skills needed to service and repair different systems of Class 4 through Class 8 trucks and tractors.

The tests offered for medium- and heavy-truck technicians are:

  • T1: Gasoline Engines
  • T2: Diesel Engines
  • T3: Drive Train
  • T4: Brakes
  • T5: Suspension & Steering
  • T6: Electrical/Electronic Systems
  • T7: Heating, Ventilation & Air Conditioning (HVAC)
  • T8: Preventative Maintenance Inspection

There are also other diesel engine areas that ASE offers certification areas for, including light trucks, transit buses, school buses, truck equipment and advanced-level specialties, such as the electronic diesel engine diagnosis specialist certification test (L2).

ASE certifications are written by industry professionals, from working technicians to manufacturers and educators. The questions are entirely job-related and test the skills needed for servicing diesel vehicles.

Master Certification

Once certification is achieved in the required testing areas for the series, Master Technician status is earned. Master medium/heavy-truck technicians are those certified in tests T2 through T8. It’s important to remember that there are recertification tests that are required every five years to maintain Master Technician status.

Certified Diesel Mechanic Salary and Job Outlook

Having a sense of the salary potential and outlook for a career you want to pursue can help you ensure it’s the right path for you. While there is no information specific to salary and job outlook for certified diesel technicians, general information about diesel mechanics can help give a starting estimate. The U.S. Bureau of Labor Statistics (BLS) is a great resource that can help give an idea of what to expect as far as median annual salary in various fields.

According to the BLS, the median annual salary for bus and truck mechanics and diesel engine specialists in the United States was $54,360 in May 2022.29 This means half of diesel technicians earned more and half earned less. Keep in mind that salary depends on several factors, including experience, employer, demand and cost of living in the area.

Total diesel technician employment is also expected to be 305,800 by 2031.48 With additional certifications on your résumé, you can stand out in the job market and look more attractive to potential employers!

Start Your Journey Toward Diesel Certification at UTI

If training to become a certified diesel technician sounds like the right move for you, enrolling in the Diesel Technology program at UTI is a great first step. You’ll earn training that you can substitute for one of the two years of work experience needed to become ASE certified and have a foundational knowledge you can continue to build upon.

Find out more when you contact an Admissions Representative today!

UTI Campuses That Offer Diesel Mechanic Training

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1) UTI is an educational institution and cannot guarantee employment or salary.

2) For program outcome information and other disclosures, visit

7) Some programs may require longer than one year to complete.

15) Manufacturer-paid advanced training programs are conducted by UTI on behalf of manufacturers who determine acceptance criteria and conditions. These programs are not part of UTI’s accreditation. Programs available at select locations.

16) Not all programs are accredited by the ASE Education Foundation.

29) UTI’s Diesel Technology Program prepares graduates for entry-level positions using the provided training, primarily as diesel technicians. Estimated annual salary shown above is for Bus and Truck Mechanics and Diesel Engine Specialists as published in the U.S. Bureau of Labor Statistics’ May 2022 Occupational Employment and Wages. Entry-level salaries are lower for UTI graduates. UTI is an educational institution and cannot guarantee employment or salary. UTI graduates’ achievements may vary. Individual circumstances and wages depend on economic factors, personal credentials, work experience, industry certifications, the location of the employer, and their compensation programs. Some UTI graduates get jobs within their field of study in positions other than as diesel truck technicians, including in industries such as heavy equipment repair, power generation, and agriculture. Salary information for the Commonwealth of Massachusetts: The average annual entry-level salary range for persons employed as Bus and Truck Mechanics and Diesel Engine Specialists (49-3031) in the Commonwealth of Massachusetts is $32,360 to $94,400 (Massachusetts Labor and Workforce Development, May 2020 data Salary information for North Carolina: The U.S. Department of Labor estimates the hourly median wage for skilled diesel technicians in North Carolina is $24.18 (Bureau of Labor Statistics, U.S. Department of Labor, May 2022 Occupational Employment and Wages, Bus and Truck Mechanics and Diesel Engine Specialists). The Bureau of Labor Statistics does not publish entry-level salary data. However, the 25th and 10th percentile of hourly earnings in North Carolina are $20.56 and $17.49, respectively.

48) The U.S. Bureau of Labor Statistics projects that total national employment for Bus and Truck Mechanics and Diesel Engine Specialists will be 305,800 by 2031. See Table 1.2 Employment by detailed occupation, 2021 and projected 2031, U.S. Bureau of Labor Statistics,, viewed October 13, 2022. UTI is an educational institution and cannot guarantee employment or salary.

Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.


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