Generator shuts down; controller shows Fault Code 151 – High Engine Temperature

Safety first: Do not open the radiator cap while hot; scalding coolant can spray out. Turn the generator to OFF and allow it to cool completely.

• Check coolant level: Inspect the coolant level in the overflow/expansion tank and at the radiator (when cool). Top up with the correct coolant mix specified by Cummins. If low, inspect for leaks at hoses, clamps, water pump, and radiator core.
• Inspect airflow: Ensure louvers, intake, and exhaust openings on the Cummins enclosure are not blocked by debris, snow, or vegetation. Clean radiator fins with low-pressure air or water from the back side to remove dirt and insects.
• Fan and belt: Verify the engine cooling fan spins freely and that the fan belt is intact and properly tensioned. Replace worn or broken belts with the correct Cummins belt part.
• Thermostat and sensor: If overheating occurs quickly after start, the thermostat may be stuck closed. Replacing the thermostat requires draining some coolant; follow the service manual. Check the coolant temperature sensor connector for corrosion or damage.
• Reset and test: After correcting issues, clear the fault and run the generator under moderate load while monitoring temperature on the controller.