Diesel service technicians and mechanics typically do the following:

• Consult with customers and read work orders to determine work required
• Plan work procedures, using technical charts and manuals
• Inspect brake systems, steering mechanisms, transmissions, engines, and other parts of vehicles
• Follow checklists to ensure that all critical parts are examined
• Read and interpret diagnostic test results to identify mechanical problems
• Repair or replace malfunctioning components, parts, and other mechanical or electrical equipment
• Perform basic care and maintenance, including changing oil, checking fluid levels, and rotating tires
• Test-drive vehicles to ensure that they run smoothly

Because of their efficiency and durability, diesel engines have become the standard in powering trucks and buses. Other heavy vehicles and mobile equipment, including bulldozers and cranes, are also powered by diesel engines, as are many commercial boats, and some passenger vehicles and pickups.

Diesel technicians handle many kinds of repairs. They may work on a vehicle's electrical system, make major engine repairs, or retrofit exhaust systems with emission control systems to comply with pollution regulations.

Diesel engine maintenance and repair is becoming more complex as engines and other components use more electronic systems to control their operation. For example, fuel injection and engine timing systems rely heavily on microprocessors to maximize fuel efficiency and minimize harmful emissions. In most shops, workers often use hand-held or laptop computers to diagnose problems and adjust engine functions. 

In addition to using computerized diagnostic equipment, diesel technicians use a variety of power and machine tools, such as pneumatic wrenches, lathes, grinding machines, and welding equipment. Hand tools, including pliers, sockets and ratchets, and screwdrivers, are commonly used.

Employers typically provide expensive power tools and computerized equipment, but workers generally acquire their own hand tools over time.

For more information on technicians and mechanics who work primarily on automobiles, see the profile on automotive service technicians and mechanics.

For more information on technicians and mechanics who work primarily on farm equipment, construction vehicles, and rail cars, see the profile on heavy vehicle and mobile equipment service technicians.

For more information on technicians and mechanics who work primarily on motorboats, motorcycles, and small all-terrain vehicles, see the profile on small engine mechanics.