Diesel Engine Diagnostics Workbook: Fuel Systems, Turbochargers, and Emissions

Diesel diagnostics requires more than reading fault codes — it requires understanding the system well enough to know which code is a symptom of a deeper problem and which indicates the actual fault. Technicians who approach diesel diagnostics as code-clearing rather than system reasoning produce comebacks and misdiagnoses that cost shops thousands of hours in rework. By the end of this course you will be able to use a diesel scan tool to interpret live data parameters for fuel system and emissions health, perform pressure and volume tests on a low-pressure fuel supply system, interpret fuel trim and IQ (injection quantity) data to evaluate injector condition, and execute a DPF diagnostic and forced regen procedure. What you will learn: - Scan tool navigation for diesel: live data PIDs relevant to fuel system, boost, EGR, and aftertreatment - Low-pressure fuel supply diagnosis: lift pump flow tests, restriction testing, and return flow measurement - Injector IQ (injection quantity) balance: reading IQ deviation values, interpreting correction ranges, and deciding repair versus replacement - High-pressure fuel system testing: rail pressure target versus actual comparison, pressure leak-down, and high-pressure pump output tests - Turbocharger diagnosis: boost pressure deviation, VGT actuator response, and compressor surge indicators - EGR diagnosis: valve flow testing, cooler efficiency evaluation, and carbon restriction assessment - DPF diagnosis: soot load percentage, backpressure readings, and forced regeneration procedure - SCR and DEF system diagnosis: reagent quality tests, doser function, and NOx sensor interpretation Each module presents a diagnostic procedure with a detailed worked example — a fictional truck with a specific complaint — tracing the diagnostic reasoning step by step. Procedure checklists are formatted for use during supervised shop diagnostic work. Written for diesel technology students and technicians who have foundational system knowledge and want to develop structured diagnostic workflow. Suitable for anyone entering diesel diagnostics work under qualified supervision. This course is educational; high-pressure diesel fuel system work involves pressures that can cause fatal injection injuries. All service procedures must be performed by qualified technicians following manufacturer safety procedures.