Controller displays F25 – Fuel filter restriction alarm

Safety first: Depressurize the fuel system and contain spills. No smoking or open flames.

• Replace fuel filters: Change the primary and secondary fuel filters using MTU-specified elements. Prime the system according to the service manual.
• Inspect fuel quality: Draw a fuel sample from the tank and check for water, sludge, or microbial growth. Arrange for fuel polishing if contamination is present.
• Check restriction switch: Inspect the differential pressure switch or sensor and its connections. Replace if it continues to indicate restriction with new filters.
• Test run: Clear the F25 alarm and run the generator under load, monitoring for recurrence.