Become A Master Diesel Mechanic - Diesel Mechanic Guide

Become A Master Diesel Mechanic

As companies throughout the United States continue to expand their diesel-powered vehicle fleets, the need for certified diesel mechanics is an ever-growing demand.

For diesel mechanics who already work in the commerce industry, attaining the certification of Master Diesel Mechanic will not only increase salary potential but will also allow for faster career advancement and greater job stability.

The requirements to become a Master Diesel Mechanic are strict, but diesel mechanics who wish to ascertain greater job mobility will enjoy the various benefits that come with certifying as a Master Diesel Mechanic.

A Master Diesel Mechanic is the primary go-to person in diagnosing mechanical problems on diesel-powered vehicles. When a vehicle is brought in for service, a Master Diesel Mechanic will inquire about the specific vehicle problems from the owner or driver.

diesel mechanic training in ohioOnce an initial diagnosis has been reached, the Master Diesel Mechanic runs the necessary tests to determine if the original hypothesis is correct. When the malfunction has been identified and the repair plan has been determined, Master Diesel Mechanics either delegate the necessary repairs to a lower level diesel mechanic or begin the repair process themselves.

The Master Diesel Mechanic designation demonstrates to potential employers that the mechanic is knowledgeable in every major component of diesel-powered vehicles, which includes the computer systems, transmissions, brakes, and electrical components. Mechanics with this designation understand how each part interacts with the other, allowing them to gain a more complete diagnosis than those who have not earned their Master Diesel Mechanic certification.

Certification Prerequisites

Before diesel mechanics are allowed to take the exam to become a Master Diesel Mechanic, they must meet a handful of prerequisites. Applicants must be able to demonstrate to the National Institute for Automotive Service Excellence (ASE) that the following prerequisites have been met.

High School Diploma or GED

Diesel mechanics who are seeking the Master Diesel Mechanic designation must have earned at least their high school diploma. Proof of graduation will have to be sent to the National Institute of Automotive Service Excellence before the applicant can continue with the certification process.


Diesel mechanics need to provide proof that they have a minimum of two years of experience before they are eligible to take the exam. Most diesel mechanics are unable to get this experience without having first earned a certificate or degree in diesel technology. Most employers prefer to hire diesel mechanics who have some post-secondary training, particularly for entry-level positions.

Most vocational schools and community colleges offer the diesel technology certification, which takes up to one year to complete. Certification covers the basic knowledge that entry-level diesel mechanics need to know before accepting their first job.

For individuals who want to show future employers their dedication to the diesel mechanic industry, an associate or bachelor’s degree in diesel technology provides a deeper understanding of the inner component workings of diesel engines.

Students spend much of their time in a lab or garage setting, and certified instructors demonstrate how to diagnose and repair the different drive train components that make up diesel engines. Some classroom work is essential for graduation, with most community colleges requiring students to take core courses in natural sciences and mathematics. For the diesel technology degree program, some of the courses include:

  • Hydraulics
  • Diesel engine technology
  • Power trains
  • Fuel systems
  • Electrical systems
  • Heavy duty brakes
  • AC systems
  • Power transmissions

The National Institute of Automotive Service Excellence allows Master Diesel Mechanic applicants to count any post-secondary training as one year of experience. Combining work experience with educational training encourages diesel mechanics to pursue their certification or degree in diesel technology.

Skill Requirements

Although not required by the ASE, diesel mechanics who are applying for the Master Diesel Mechanic designation should have certain interpersonal and technological skills in order to excel in the position.

Customer Service

If diesel mechanics do not enjoy working with vehicle drivers and owners, becoming certified as a Master Diesel Mechanic may not be the right choice for them. Since Master Diesel Mechanics speak directly with the owners of diesel-powered vehicles, exceptional customer service skills are necessary, allowing the mechanics to diagnose the problem and maintain a positive experience for the client.

Computer Systems

Before taking the Master Diesel Mechanic exam, diesel mechanics should be thoroughly familiar with automobile computer systems. Part of the exam covers the electronic components of computer systems on diesel engines, and diesel mechanics need to prove they are proficient in electrical repair in order to pass the exam.

Master Diesel Mechanic Examination

A diesel mechanic will be eligible to take the Master Diesel Mechanic exam once all prerequisites have been met. In order to earn the Master Diesel Mechanic certification, an individual must pass eight examinations. The eight topics covered in the exam include:

  • Engine performance
  • Heating and air conditioning
  • Electrical/electronic systems
  • Brakes
  • Suspension and steering
  • Manual drive train and axles
  • Automatic transmission
  • Engine repair

Each of the eight topics consists of up to 50 multiple choice questions, with each topic having its own exam that can be taken separately or together with the other topics. Prior to registration, diesel mechanics need to pay the separate registration fees for each part of the exam that they plan on taking.

Once diesel mechanics have successfully completed and passed all eight sections, they will earn the Master Diesel Mechanic designation. The law requires Master Diesel Mechanics to renew their certification every five years, requiring them to retake all eight exams.

For diesel mechanics looking to further their career in the mechanic industry, certifying as a Master Diesel Mechanic will help them reach their desired career aspirations. From becoming a shop supervisor to owning a diesel repair garage, Master Diesel Mechanics have several job opportunities available to them throughout the nation.