Lesson 1Engine coolant temperature and air intake temperature: impact on fuelling and emissions control behaviourLearn how coolant and intake air temperatures influence fuelling, timing, and emissions strategies. Understand warm-up behaviour, sensor plausibility checks, and how incorrect readings cause hard starts, smoke, or poor regeneration control.
Cold start temperature expectationsECT vs IAT plausibility comparisonTemperature effects on injection timingImpact on EGR and DPF strategiesDetecting biased or stuck temp sensorsLesson 2Intake manifold pressure and ambient pressure: expected values at idle and under load, and relationships to boostStudy intake manifold and ambient pressure data to verify boost system performance. Learn expected idle and load values, altitude effects, and how to use pressure relationships to detect boost leaks, stuck turbos, or inaccurate MAP sensors.
Ambient pressure and altitude effectsExpected MAP at key load pointsUsing KOEO readings for sensor checksPatterns indicating boost leaksDetecting MAP sensor bias or driftLesson 3Exhaust Back Pressure (or DPF differential pressure): expected ranges, regeneration triggers, and signs of restrictionLearn how to interpret exhaust back pressure and DPF differential pressure PIDs. Understand normal ranges at idle and load, how regeneration affects readings, and how rising pressure trends reveal exhaust restrictions or failing DPF systems.
Normal back pressure at idle and loadDPF differential pressure thresholdsPressure behavior during regenerationIdentifying exhaust restrictions upstreamSensor and hose fault differentiationLesson 4Mass Air Flow (MAF) or Intake Air Mass: expected ranges, sensor response to throttle changes, and impact on fuellingExplore how to interpret MAF or calculated air mass readings under various loads. Learn expected ranges, response to throttle changes, and how airflow data interacts with EGR and boost to guide accurate fuelling and smoke control diagnosis.
Baseline MAF at idle and no-loadMAF response to snap throttle testsMAF changes with EGR on and offUsing MAF to confirm boost deliveryDetecting contaminated MAF sensorsLesson 5Fuel rail pressure sensor voltage/PID and rail pressure demand vs actual comparisonUnderstand how to read rail pressure sensor voltage and pressure PIDs, and compare commanded versus actual values. Learn to recognise slow response, overshoot, and low-pressure events that indicate pump, regulator, leak, or sensor problems.
Typical rail pressure at idle and WOTSensor voltage to pressure relationshipCommanded vs actual pressure graphsDiagnosing slow pressure responseIdentifying leaks and relief valve issuesLesson 6EGR position and flow indicators: typical position ranges, response to commands, and symptoms of EGR faultsUnderstand how to read EGR position and flow data, compare commanded versus actual values, and recognise slow or stuck responses. Learn how EGR faults affect drivability, emissions, and how to separate EGR issues from boost or airflow problems.
Typical EGR position ranges by loadCommanded vs actual EGR correlationSymptoms of stuck-open EGR valvesSymptoms of stuck-closed EGR valvesUsing MAF and MAP to confirm EGR flowLesson 7Injector correction/individual cylinder trim: normal small trims, large corrections indicating injector/ECU/pressure issuesLearn how injector correction values reflect cylinder balance, fuelling accuracy, and combustion quality. Understand normal trim ranges, when large deviations are a concern, and how to link patterns to mechanical, electrical, or ECU-related faults.
Normal trim ranges at idle and cruiseInterpreting positive vs negative trimsPatterns indicating faulty injectorsDistinguishing ECU vs mechanical issuesEffects of rail pressure errors on trimsLesson 8Engine RPM, throttle position, and accelerator pedal position: correlation checks and drive-by-wire sanityExplore how RPM, throttle position, and accelerator pedal signals interact in drive-by-wire systems. Learn to spot correlation faults, dead spots, and latency that cause hesitation, limp mode, or unsafe acceleration behaviour during road tests.
Expected idle and cruise RPM valuesDual-track pedal sensor agreementThrottle plate vs pedal position trackingDetecting signal dropouts and noiseDrive-by-wire faults causing limp modeLesson 9Turbo boost pressure and wastegate control: expected boost curves, lag under load, and diagnosing boost leaksUnderstand turbo boost pressure and wastegate or VGT control data. Learn expected boost curves, acceptable lag, and how to use scan tool graphs to separate boost leaks, sticking actuators, and control issues from genuine engine load problems.
Target vs actual boost comparisonAcceptable turbo lag characteristicsUsing actuator command PIDsPatterns of boost leaks under loadOverboost and underboost fault cluesLesson 10Fuel temperature and fuel temperature sensor behaviour: why it matters for fuelling compensation and expected rangesLearn why fuel temperature is monitored, how it affects density and compensation, and what ranges are typical. Understand sensor behaviour during hot soak, recirculation, and how abnormal readings can mislead rail pressure and quantity control.
Normal fuel temperature operating rangeHot soak and recirculation effectsFuel temp influence on density modelsInteraction with rail pressure controlIdentifying faulty temp sensor signalsLesson 11High-pressure rail pressure: normal ranges, expected behaviours under load, and signs of low rail pressure issuesStudy high-pressure rail behaviour across operating conditions. Learn normal pressure ranges, ramp-up times, and stability under load, and how deviations point to worn pumps, injector leakage, control valve faults, or supply side problems.
Pressure ramp-up during crankingStability at idle and steady cruisePressure response to rapid load stepsSigns of internal injector leakagePump wear vs suction restriction cluesLesson 12Battery voltage and crank/charge system parameters: effects on high-pressure pump and injector driver performanceUnderstand how battery voltage and charging data affect high-pressure pump output and injector drivers. Learn to evaluate cranking voltage, alternator regulation, and how low voltage can mimic fuel or sensor faults during diagnosis.
Minimum cranking voltage thresholdsStarter current draw and RPM impactAlternator output and load responseVoltage sensitivity of injector driversLow-voltage induced false DTCs
