Pages for school buses
Starting
Why is my Cummins hard to start when it is cold?
Troubleshoot →StartingMy diesel cranks but will not start. Where do I begin?
Troubleshoot →SmokeWhat does white smoke from my diesel mean?
Troubleshoot →SmokeWhy is my diesel blowing black smoke?
Troubleshoot →SmokeWhat does blue or gray-blue smoke from a diesel mean?
Troubleshoot →Power & drivabilityWhy did my diesel lose power or go into limp mode?
Troubleshoot →Power & drivabilityWhy does my diesel idle rough or miss?
Troubleshoot →Fuel systemMy water-in-fuel light came on. What should I do?
Troubleshoot →Fuel systemWhy is my diesel oil level rising, and does it smell like fuel?
Troubleshoot →CoolingMy diesel is losing coolant with no visible leak. Why?
Troubleshoot →EmissionsWhat is DPF regeneration and why does my truck keep doing it?
Troubleshoot →Fuel systemDid my diesel fuel gel? How do I prevent it?
Troubleshoot →EmissionsWhy does my diesel say DEF fault or "speed limited"?
Troubleshoot →EmissionsHow do I know if my diesel NOx sensor is bad?
Troubleshoot →EmissionsCan a clogged EGR valve cause rough running and low power?
Troubleshoot →Power & drivabilityWhy is my diesel turbo whistling or hissing under load?
Troubleshoot →Power & drivabilityWhat causes a diesel knock or injector "nailing" noise?
Troubleshoot →Fuel systemCan a plugged fuel filter cause low power on a diesel?
Troubleshoot →Fuel systemHow does air get into diesel fuel lines, and how do I fix it?
Troubleshoot →Power & drivabilityHow much oil should my diesel use, and when is it too much?
Troubleshoot →Power & drivabilityHow do I tell if my diesel has excessive blow-by?
Troubleshoot →CoolingWhat is cavitation and liner pitting in a diesel cooling system?
Troubleshoot →Guides & checklistsWhat maintenance does a diesel need that a gas engine does not?
Troubleshoot →Guides & checklistsHow do I get my diesel ready for winter?
Troubleshoot →EmissionsWhy does idling cause DPF problems on diesel school buses?
Troubleshoot →EmissionsWhy did Navistar MaxxForce engines have so many EGR problems?
Troubleshoot →Engines you will find in school buses
Cummins · Navistar / International · Detroit
Where this comes from
Last reviewed 2026-10-19. General information only: confirm with your service information and a qualified diesel technician.