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Diesel troubleshooting library

What is your diesel doing?

Start from the symptom. Each page answers one real question in plain English: the easy checks first, the likely causes next, and when it is time for a qualified diesel tech. Cummins first, then Power Stroke, Duramax and the rest: semis, motorhomes, school buses, tractors, boats and generators.

    Most searched questions

    Smoke

    What does white smoke from my diesel mean?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Starting

    Why is my Cummins hard to start when it is cold?

    CumminsAll dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Power & drivability

    Why did my diesel lose power or go into limp mode?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

    Why does my diesel say DEF fault or "speed limited"?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

    What is DPF regeneration and why does my truck keep doing it?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Fuel system

    Why is my diesel oil level rising, and does it smell like fuel?

    CumminsAll dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Cooling

    Why does my diesel run hot when towing?

    All dieselsPickupsRV / diesel pushersTroubleshoot →    Fuel system

    Did my diesel fuel gel? How do I prevent it?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Power & drivability

    Why is my diesel turbo whistling or hissing under load?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Guides & checklists

    What should I check before buying a used diesel truck?

    All dieselsPickupsRV / diesel pushersVans & carsTroubleshoot →    Power & drivability

    What is wet stacking on a diesel generator or idling truck?

    All dieselsGeneratorsRV / diesel pushersMarine+ moreTroubleshoot →    Front end

    My Ram shakes violently after a bump. Is that the engine?

    CumminsPickupsTroubleshoot →

    All 43 symptoms and guides, with filters →

    Pick your engine

    Cummins8 specific pages + common symptomsPower Stroke5 specific pages + common symptomsDuramax2 specific pages + common symptomsGM 6.2 / 6.51 specific page + common symptomsRam EcoDiesel 3.01 specific page + common symptomsJeep EcoDieselEngine hub + common symptomsNissan Titan XD 5.0Engine hub + common symptomsNavistar / International1 specific page + common symptomsDetroitEngine hub + common symptomsPACCAREngine hub + common symptomsVolvo / MackEngine hub + common symptomsIsuzu / HinoEngine hub + common symptomsMercedes / Sprinter1 specific page + common symptomsVW TDIEngine hub + common symptoms

    Or your vehicle

    Pickups37 pagesSemi trucks26 pagesRV / diesel pushers31 pagesSchool buses26 pagesTractors / ag27 pagesMarine16 pagesGenerators18 pagesVans & cars29 pages

    How these pages work

    1. The question

    Every page starts with something owners actually search for, like white smoke or a cold hard start.

    2. Easy checks

    Things you can look at safely without special tools: levels, filters, connections, codes.

    3. When to see a pro

    High-pressure fuel and hot exhaust are no place to guess. We say plainly when a diesel tech should take over.

    Black 2014-2016 Ram 3500 Cummins crew cab dually towing a car-hauler trailer
    Towing is where diesels earn their keep, and where weak cooling and fuel systems show up first. Photo: Bull-Doser, Public domain, via Wikimedia Commons.