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All symptoms and guides

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    Starting

    Starting

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

    CumminsAll dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Starting

    My diesel cranks but will not start. Where do I begin?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Starting

    How do I know if my glow plugs or grid heater have failed?

    CumminsGM 6.2 / 6.5All dieselsPickupsVans & carsTractors / ag+ moreTroubleshoot →

    Smoke

    Smoke

    What does white smoke from my diesel mean?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Smoke

    Why is my diesel blowing black smoke?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Smoke

    What does blue or gray-blue smoke from a diesel mean?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →

    Power & drivability

    Power & drivability

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

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

    Why does my diesel idle rough or miss?

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

    Why is my diesel turbo whistling or hissing under load?

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

    What causes a diesel knock or injector "nailing" noise?

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

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

    All dieselsGeneratorsRV / diesel pushersMarine+ moreTroubleshoot →    Power & drivability

    Why is my Cummins exhaust brake not working?

    CumminsPickupsRV / diesel pushersTroubleshoot →    Power & drivability

    How much oil should my diesel use, and when is it too much?

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

    How do I tell if my diesel has excessive blow-by?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →

    Fuel system

    Fuel system

    My water-in-fuel light came on. What should I do?

    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 →    Fuel system

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

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Fuel system

    How do I know if my 24-valve Cummins lift pump is failing?

    CumminsPickupsTroubleshoot →    Fuel system

    Can a plugged fuel filter cause low power on a diesel?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Fuel system

    How does air get into diesel fuel lines, and how do I fix it?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Fuel system

    What is the CP4 fuel pump issue on diesel trucks?

    Power StrokeDuramaxRam EcoDiesel 3.0PickupsTroubleshoot →

    Cooling

    Cooling

    Why does my diesel run hot when towing?

    All dieselsPickupsRV / diesel pushersTroubleshoot →    Cooling

    My diesel is losing coolant with no visible leak. Why?

    DuramaxPower StrokeAll dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Cooling

    How do I know if my 6.0 Power Stroke EGR cooler is failing?

    Power StrokePickupsVans & carsTroubleshoot →    Cooling

    Why does my diesel truck transmission get hot or shift hard when towing?

    All dieselsPickupsRV / diesel pushersTroubleshoot →    Cooling

    What is cavitation and liner pitting in a diesel cooling system?

    All dieselsSemi trucksTractors / agMarine+ moreTroubleshoot →    Cooling

    Why do 6.0 Power Stroke head gaskets fail?

    Power StrokePickupsVans & carsTroubleshoot →    Cooling

    What are the common 6.4 Power Stroke radiator and DPF problems?

    Power StrokePickupsTroubleshoot →    Cooling

    Why is my marine diesel overheating?

    MarineGeneratorsTroubleshoot →    Cooling

    Why does my diesel pusher motorhome run hot on grades?

    CumminsRV / diesel pushersTroubleshoot →

    Emissions

    Emissions

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

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

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

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

    How do I know if my diesel NOx sensor is bad?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

    Can a clogged EGR valve cause rough running and low power?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

    Is it legal to delete the DPF, EGR or DEF on my diesel?

    All dieselsPickupsSemi trucksRV / diesel pushers+ moreTroubleshoot →    Emissions

    My tractor wants a parked regen or says DEF low. What do I do?

    Tractors / agTroubleshoot →    Emissions

    Why does idling cause DPF problems on diesel school buses?

    CumminsSchool busesTroubleshoot →    Emissions

    Does my Sprinter diesel need the BlueTEC emissions modification?

    Mercedes / SprinterVans & carsTroubleshoot →    Emissions

    Why did Navistar MaxxForce engines have so many EGR problems?

    Navistar / InternationalSemi trucksSchool busesTroubleshoot →

    Front end

    Front end

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

    CumminsPickupsTroubleshoot →

    Guides & checklists

    Guides & checklists

    What maintenance does a diesel need that a gas engine does not?

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

    How do I get my diesel ready for winter?

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

    What should I check before buying a used diesel truck?

    All dieselsPickupsRV / diesel pushersVans & carsTroubleshoot →

    Last reviewed 2026-10-19. General information only: confirm with your service information and a qualified diesel technician.