Torchora
Back to Home

Key Responsibilities and Required Skills for Diesel Technician

💰 $ - $

AutomotiveDieselMaintenanceTransportation

🎯 Role Definition

A Diesel Technician (diesel mechanic) performs diagnostic, maintenance, repair, and preventative service on diesel engines and heavy-duty commercial vehicles including trucks, buses, trailers, off-road equipment and power units. This role emphasizes strong mechanical and electrical troubleshooting skills, use of computerized diagnostic tools (e.g., Cummins INSITE, Detroit Diagnostic Link, CAT ET), compliance with DOT/EPA/OSHA safety regulations, and excellent documentation and customer communication. Diesel Technicians support fleet uptime, reduce repair turnaround time, and contribute to safe, compliant equipment operations.

📈 Career Progression

Typical Career Path

Entry Point From:

  • Automotive Technician (gasoline mechanics transitioning to diesel)
  • Vocational/Trade School Diesel Mechanic Graduate or Apprentice
  • Fleet Maintenance Assistant or Service Technician

Advancement To:

  • Senior Diesel Technician / Lead Technician
  • Shop Foreman or Lead Mechanic
  • Fleet Maintenance Supervisor / Manager
  • Field Service Technician / Mobile Diesel Technician
  • Manufacturer or OEM Certified Technician / Trainer

Lateral Moves:

  • Heavy Equipment Technician (construction or agricultural)
  • Service Writer / Dispatcher
  • Parts Specialist or Inventory/Procurement Coordinator

Core Responsibilities

Primary Functions

  • Diagnose complex engine, transmission, drivetrain, and electrical faults using computerized diagnostic tools (Cummins INSITE, Detroit Diesel Diagnostic Link, CAT ET, JPRO) and multimeters, interpreting fault codes, freeze-frame data, and live sensor values to determine repair plans.
  • Perform routine and preventive maintenance (PM) services on heavy-duty diesel vehicles including oil changes, filter replacements, fluid checks, fuel system servicing, and scheduled inspections to meet fleet uptime targets.
  • Disassemble, inspect, rebuild, and install diesel engines, turbochargers, fuel injection systems, cylinder heads, and related components to OEM or manufacturer specifications, ensuring correct torque and sealant application.
  • Inspect, diagnose, repair, and replace transmission systems (manual and automatic), clutches, differentials, transfer cases and related driveline components, including fluid flushes and reconditioning.
  • Troubleshoot and repair heavy vehicle electrical systems including alternators, starters, wiring harnesses, ECMs/ECUs, sensors, relays, and control modules, and update or reflash software as required.
  • Maintain and repair air brake systems, ABS systems, compressors, reservoirs, valves, and airlines; perform accurate leak tests, adjustments, and corrective actions to ensure DOT compliance.
  • Service and repair suspension, steering, and chassis systems (leaf springs, shock absorbers, kingpins, tie rods, bushings) including alignment checks and steering geometry adjustments.
  • Diagnose and repair hydraulic systems, PTOs, hoists, lift gates and components on commercial vehicles, including identifying leaks, replacing hoses, seals and pumps and verifying system pressures.
  • Perform complete brake overhauls, drum and disc brake service, lathe rotor/drum machining coordination, and ensure brake performance meets safety specifications.
  • Conduct DOT pre-trip and post-trip inspections, complete required documentation and remediate defects within mandated time frames to maintain roadworthiness and regulatory compliance.
  • Prepare accurate repair estimates and cost breakdowns; communicate findings and repair options clearly to service advisors, fleet managers or customers; obtain approval before proceeding with non-routine work.
  • Conduct road tests and load tests to validate repairs, confirm proper operation under real-world conditions, and document performance metrics and anomalies for quality control.
  • Order parts and consumables, manage parts requests, verify correct part numbers, and coordinate with parts team to minimize vehicle downtime and keep repair schedules on track.
  • Maintain detailed service records and digital repair logs in the shop management system (e.g., Fleetio, Mitchell, R.O. software), including hours worked, parts used, warranty items, and next recommended service.
  • Perform welding and fabrication tasks (MIG/TIG/oxy-acetylene) to repair exhaust systems, mounts, brackets, custom brackets, and structural components as needed while ensuring structural integrity and safety.
  • Follow established safety protocols, use personal protective equipment (PPE), implement lockout/tagout procedures, and participate in safety meetings to reduce workplace incidents and maintain a safe shop environment.
  • Inspect and repair HVAC and refrigeration units on refrigerated trailers and trucks, including compressor, evaporator, condenser and control diagnostics for reefer units.
  • Calibrate and use precision measuring tools (micrometers, dial indicators, bore gauges) to verify tolerances and ensure components meet OEM specifications during reassembly.
  • Mentor and train junior technicians and apprentices by demonstrating best practices, diagnostic techniques, and safe repair procedures, contributing to a high-performing team and skills transfer.
  • Participate in continuous improvement initiatives by identifying recurring failures, recommending corrective actions, and documenting root cause analyses to reduce repeat repairs and operating costs.
  • Manage time effectively across multiple repair orders, prioritize emergency or roadside repairs, and coordinate with dispatch to optimize fleet availability and minimize service disruptions.
  • Inspect exhaust after-treatment systems (DPF, SCR), diagnose regeneration issues, replace sensors and components, and ensure emissions systems meet EPA and local environmental regulations.
  • Support mobile service or on-site repairs at customer locations, providing roadside troubleshooting, on-the-road repairs, and safe vehicle recovery or towing coordination when necessary.
  • Perform final quality inspections before vehicle release, verify that all work orders are complete, and ensure customer sign-off and satisfaction with repairs and service experience.

Secondary Functions

  • Assist fleet managers by compiling repair trend reports, cost-of-repair analyses, and recommendations for preventive actions to improve fleet reliability.
  • Collaborate with parts, service advisors and warranty administrators to process warranty claims, return defective parts, and document warranty repair details.
  • Participate in periodic shop equipment maintenance and calibration (hoists, brake testers, diagnostic computers) to ensure tools are reliable and diagnostics remain accurate.
  • Support safety audits and compliance programs, participate in OSHA/DOT training, and contribute to continuous safety improvements across the maintenance operation.
  • Contribute to the development of standard work procedures, checklists and technical documentation to streamline troubleshooting and repair workflows.
  • Provide technical input for purchasing decisions on tools, diagnostic licenses and shop investments based on recurring failure modes and technician feedback.
  • Help coordinate and schedule preventive maintenance visits, mobile service routes, and downtime windows with operations teams to align repairs with business needs.
  • Assist with inventory control by reporting low-stock items, obsolete parts, and recurring fasteners or seals to reduce delays in repairs.
  • Act as a subject matter resource to non-technical staff and clients, explaining technical constraints, lead times, and safety concerns in understandable terms.
  • Engage in professional development by attending manufacturer or OEM training sessions, certification courses, and vendor-driven seminars to maintain current technical competency.

Required Skills & Competencies

Hard Skills (Technical)

  • Diesel engine diagnosis and overhaul — experienced in reading compression, leak-down tests, and interpreting diagnostic trouble codes.
  • Proficient with computerized diagnostic software: Cummins INSITE, Detroit Diesel Diagnostic Link (DDDL), CAT ET, JPRO, Snap-on Solus or equivalent scan tools.
  • Heavy vehicle electrical systems troubleshooting — wiring diagrams, ECM/PCM programming, CAN-bus diagnostics and sensor replacement.
  • Air brake and ABS system maintenance and repair, including knowledge of S-cam brakes, foundation brakes, compressors, valves and leak detection procedures.
  • Transmission and driveline repair — experience with manual/automatic transmissions, clutch systems, torque converters and differentials.
  • Hydraulic systems and PTO servicing — pump replacement, seal repairs, hose routing and pressure testing.
  • Welding and metal fabrication (MIG, TIG, oxy-acetylene) with the ability to fabricate brackets, mounts and exhaust repairs.
  • Preventive maintenance and DOT inspection competency — ability to perform PM checklists and annotate safety-critical defects.
  • Emissions after-treatment systems expertise — DPF, SCR, EGR troubleshooting and regeneration procedures.
  • Use of precision measuring tools — micrometers, bore gauges, dial indicators and torque wrenches to OEM tolerances.
  • Experience with shop management and maintenance software (e.g., Fleetio, Mitchell 1, R.O. systems) for work orders and record keeping.
  • HVAC / refrigeration system repair for transport refrigeration units (reefer units) — compressor, evaporator, thermostatic controls.
  • Familiarity with OEM service manuals, TSBs (Technical Service Bulletins), and parts catalogs to ensure correct repair processes.
  • Knowledge of DOT, EPA and OSHA regulations as they apply to vehicle inspections, emissions and workplace safety.
  • Ability to perform road tests and interpret dynamic symptoms to validate repairs and adjustments.

Soft Skills

  • Strong problem-solving and analytical thinking with the ability to isolate root causes and implement durable solutions.
  • Clear verbal and written communication skills for interacting with customers, fleet managers and coworkers.
  • Time management and organizational skills to prioritize tasks, manage multiple tickets, and meet service-level expectations.
  • Detail-oriented and quality-focused — committed to thorough inspections, accurate documentation and right-first-time repairs.
  • Team player mentality who can collaborate across parts, service, and operations while mentoring less experienced technicians.
  • Customer service orientation — able to explain technical issues in plain language and maintain a professional demeanor.
  • Adaptability and continuous learning mindset to keep pace with evolving diesel and vehicle technologies.
  • Safety-first attitude with demonstrated adherence to PPE, lockout/tagout and safe lifting procedures.
  • Reliability and accountability — consistently punctual, adheres to scheduled shifts and completes assigned work.
  • Initiative to identify efficiency opportunities, suggest improvements and contribute to continuous improvement projects.

Education & Experience

Educational Background

Minimum Education:

  • High school diploma or GED plus completion of a recognized diesel or heavy equipment vocational program or equivalent on-the-job training.

Preferred Education:

  • Associate degree or certificate in Diesel Technology, Heavy Equipment Technology, or Automotive Technology.
  • Manufacturer-specific training or certifications (Cummins, Detroit Diesel, Caterpillar, Volvo, PACCAR).
  • ASE Certifications (A1–A9 series, especially A6 Heavy/Medium Truck Systems) or equivalent credentials.

Relevant Fields of Study:

  • Diesel Technology
  • Heavy Equipment Mechanics
  • Automotive Technology
  • Electrical / Electronics
  • Welding and Fabrication

Experience Requirements

Typical Experience Range:

  • Entry-level: 0–2 years with vocational training or apprenticeship.
  • Mid-level: 2–5 years performing diesel/heavy-duty repairs and PM work.
  • Senior-level: 5+ years with advanced diagnostics, supervisory responsibilities or OEM certifications.

Preferred:

  • 3+ years of experience in commercial vehicle or fleet maintenance environments.
  • Proven experience with computerized diagnostics and OEM repair procedures.
  • Prior experience with DOT inspections, on-road repairs, mobile service, or heavy-equipment maintenance preferred.
Explore More Careers