E9 224 — Max thermostat activated or flue/high limit thermostat activated

What does E9 224 mean?

The maximum thermostat has been activated, often due to a flue gas thermostat overheat or activation of the high limit thermostat. This is a safety shutdown.

• Flue gas overheating.
• System overheating (high limit thermostat).
• Faulty thermostat sensor.
• Restricted water flow.

Click steps to track your progress.

1. 1

   Turn off the boiler and let it cool down completely.

2. 2

   Check that your boiler's pressure is within the recommended range.

3. 3

   Ensure all radiators are fully open and there are no blockages in the system.

4. 4

   Reset the boiler. If the fault reoccurs, contact a Gas Safe registered engineer for inspection.