Controller displays “Low Engine Temp” or “Engine Not Warmed Up”; unit may not transfer load or may run longer in exercise mode.

Safety first: Turn generator OFF and open main breaker. Allow engine to cool before working on coolant components.

• Check block heater power: Verify that the block heater is plugged into a live receptacle or hardwired circuit. Check the breaker or GFCI feeding the heater.
• Feel heater operation: After 30–60 minutes of being energized, the block heater and nearby coolant hoses should feel warm to the touch. If not, the heater may have failed.
• Thermostat: If the engine takes an excessively long time to reach operating temperature, the thermostat may be stuck open. Replacement requires draining some coolant and should follow Kohler procedures.
• Sensor and wiring: Inspect the coolant temperature sensor connector and harness for corrosion or damage. Reseat connectors to the controller.

While low temperature is less immediately damaging than overheating, it can cause poor performance and wet stacking. Have a technician replace a failed block heater or thermostat as needed.