F18
MTU Onsite Energy High Exhaust Gas Temperature

Controller displays F18 – Exhaust temperature high alarm/shutdown

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Overload condition, Restricted exhaust system, Incorrect fuel injection timing, Faulty exhaust temperature sensor

How to Fix / Troubleshooting

Safety first: Exhaust components are extremely hot. Allow cooling time and wear heat-resistant gloves.

  • Check load: Verify that the generator load does not exceed the MTU nameplate rating. Reduce load if necessary.
  • Inspect exhaust system: Look for crushed, blocked, or excessively long exhaust piping that could increase backpressure.
  • Sensor check: Compare exhaust temperature readings between cylinders (if multiple sensors) and with an infrared thermometer. Replace any faulty thermocouples or sensors.
  • Air and fuel system: Ensure air filters are clean and fuel quality meets MTU specifications. Poor combustion can raise exhaust temperature.
  • Professional tuning: If high exhaust temperature persists, have an MTU technician check injection timing and turbocharger performance.
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Repair Difficulty

Hard 4/5

Required Part

Exhaust Temperature Sensor
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