Generator shuts down shortly after starting; controller displays F04 High Engine Temperature.

Safety first: An overheated engine can cause burns and pressure release. Turn the unit OFF, open the main breaker, and allow the engine to cool completely before opening the radiator cap or working near the exhaust.

• Check coolant level: Inspect the coolant reservoir and radiator (if accessible) and top up with the Siemens-specified coolant mixture. Never open a hot radiator cap; wait until cool.
• Inspect airflow: Check that the generator enclosure louvers and radiator fins are not blocked by leaves, dust, or debris. Clean the radiator fins gently with low-pressure air or water from the back side to avoid bending fins.
• Verify cooling fan operation: During a test run, observe whether the engine-driven or electric cooling fan operates. If the fan does not spin, inspect the fan belt (if belt-driven) for breakage or slippage and replace if worn. For electric fans, check the fan relay and wiring harness.
• Check coolant temperature sensor: Locate the coolant temperature sensor on the engine. Inspect the connector for corrosion or loose pins. If F04 appears immediately on a cold engine, the sensor may be shorted; replace it with a Siemens-approved sensor.
• Retest: After corrections, clear F04 and run the generator under light load while monitoring temperature. If overheating persists, the water pump or thermostat may be failing and should be serviced by a technician.