⚠️ Rules: - No skipping steps - Explain WHY you chose your answers - Bonus if you call out the traps 👀 Comment your answers (e.g. B → B → C → B) Customer Concern: Intermittent loss of power under load. Feels like turbo drops out, returns after key cycle. Fault Code: - P0299 – Turbo Underboost What we know: - Normal at light throttle - Under load → power loss (limp mode) - Key cycle restores power - No smoke - No obvious boost leaks found visually Step 1: Where do you start? Pick ONE: A) Replace turbocharger B) Smoke test intake system C) Replace boost pressure sensor D) Clear codes and road test again Step 2: You perform a smoke test Result: No leaks found What next? A) Turbo must be faulty → replace B) Check live data for requested vs actual boost C) Replace wastegate actuator D) Replace intercooler Step 3: Live Data Results - Requested Boost: 220 kPa - Actual Boost: 140 kPa (under load) - Boost Control Duty: 90%+ What does this tell you? A) Sensor fault (incorrect reading) B) ECU not requesting boost C) System trying to make boost but can’t achieve it D) Fuel system issue Step 4: Final Direction What’s your next TEST? A) Replace turbo B) Command wastegate actuator and verify movement C) Replace MAP sensor D) Check spark plugs

Vehicle towed in with a crank, no start condition. Initial checks: - Battery low → supported with jump pack (no change) - Engine fires on ether → mechanical condition OK Scan results: - P1604 – Start ability Malfunction First Direction: Fuel System - Fuel sample taken → contaminated (kerosene smell) - Filter removed → debris + metal present - External clean diesel supply connected → still no start - No fuel movement during cranking Re-test & Re-think Second scan: - P062D – Injector Driver Circuit Performance - P0627 – Fuel Pump Control Circuit Now we shift from fuel supply → control issue ⚡ The Actual Fault Using OEM data: - Low voltage at ECU injector driver pins (+BD1 / +BD2) - Relay control side OK - But no power feed to the circuit 👉 Root cause:25A fuse missing ✅ Fix - Installed correct fuse - Voltage restored at ECU - Codes cleared - Engine starts normally Takeaway Contaminated fuel was a real issue… but not THE issue Diagnose the system, not the symptom This could’ve easily turned into: - Pump replacement - Injector replacement - ECU replacement Instead… it was a missing fuse. 👇 Discussion At what point would you have shifted from fuel diagnosis → electrical control?