High School

A high school diploma is the minimum requirement to land a job that offers growth possibilities, a good salary, and challenges. In addition to automotive and shop classes, high school students should take mathematics, English, and computer classes. Adjustments and repairs to many car components require the mechanic to make numerous computations, for which good mathematical skills will be essential. Diesel mechanics must be voracious readers in order to stay competitive; there are many must-read volumes of repair manuals and trade journals. Computer skills are also important, as computers are common in most repair shops. 

Postsecondary Training

Employers prefer to hire those who have completed some kind of formal training program in diesel mechanics, or in some cases automobile mechanics—usually a minimum of two years' education in either case. A wide variety of such programs are offered at community colleges, vocational schools, independent organizations, and manufacturers. Most accredited programs include periods of internship.

Some programs are conducted in association with truck and heavy equipment manufacturers. Students combine work experience with hands-on classroom study of up-to-date equipment provided by manufacturers. In other programs students alternate time in the classroom with internships at manufacturers. Although these students may take up to four years to finish their training, they become familiar with the latest technology and also earn modest salaries as they train.

Although postsecondary training programs are more widely available and popular today, some mechanics still learn the trade on the job as apprentices. Their training consists of working for several years under the guidance of experienced mechanics. Trainees usually begin as helpers, lubrication workers, or service station attendants, and gradually acquire the skills and knowledge necessary for many service or repair tasks. However, fewer employers today are willing to hire apprentices because of the time and cost it takes to train them. Those who do learn their skills on the job inevitably require some formal training if they wish to advance and stay in step with the changing industry. 

Other Education or Training

To maintain and increase their skills and to keep up with new technology, diesel mechanics must regularly read service and repair manuals, industry bulletins, and other publications. They must also be willing to take part in training programs given by manufacturers, at vocational schools, or by professional associations (such as the Association of Diesel Specialists). Those who have certification must periodically retake exams to keep their credentials. Frequent changes in technology demand that mechanics keep up to date with the latest training.

Certification or Licensing

One indicator of quality for entry-level mechanics recognized by everyone in the industry is certification by the National Institute for Automotive Service Excellence. There are eight areas of certification available in medium-heavy truck repair: Gasoline Engines, Diesel Engines, Drive Train, Brakes, Suspension & Steering, Electrical/Electronic Systems, Heating, Ventilation & Air Conditioning, and Preventive Maintenance Inspection. There are eight areas of certification available in transit bus repair: Compressed Natural Gas Engines, Diesel Engines, Drive Train, Brakes, Suspension & Steering, Electrical/Electronic Systems, Heating Ventilation & Air Conditioning, and Preventive Maintenance & Inspection (PMI) (50). Applicants must have at least two years of experience in the field and pass the examinations related to their specialty. To maintain their certification, mechanics must retake the examination for their specialties every five years. 

Other Requirements

Diesel mechanics need a Class A driver's license.

Experience is gained during training programs or postsecondary education to earn an associate's degree, and through internships and on-the-job training.

Diesel mechanics must be patient and thorough, have excellent troubleshooting skills to deduce the cause of system malfunctions, be detail oriented, have excellent manual dexterity, and be willing to continue to learn throughout their careers. They also need to be in good shape and possess physical strength because they often have to work in tight spaces and lift heavy parts and tools, such as exhaust system components.