F.93 - Poor combustion quality

What does F.93 mean?

The combustion regulation system has detected poor combustion quality, which can increase the risk of carbon monoxide (CO) poisoning.

• Incorrect gas restrictor installed for the gas family.
• Flue gas recirculation.
• Mass flow sensor/Venturi defective (wet, blocked).
• Incorrect CO2 content.

Click steps to track your progress.

1. 1

   Press the reset button on the boiler display up to three times to try and clear the fault.

2. 2

   Ensure the condensate duct is not blocked and clear it if necessary.

3. 3

   Contact customer service immediately. This fault relates to poor combustion quality, which is a safety concern.

4. 4

   A qualified technician will need to perform a gas family check, adjust CO2 content, and check for correct gas restrictor and a functional mass flow sensor/Venturi.