Boiler shows E9; often associated with low water content or dry firing

Safety: Do not operate the boiler with suspected dry firing; this can damage the heat exchanger.

• 1. Check and refill pressure: Verify system pressure and refill to the recommended level.
• 2. Bleed boiler and radiators: Remove air from the system, starting with the boiler's built-in air vent and then radiators.
• 3. Inspect for leaks: Look for visible leaks and check the safety valve discharge pipe for signs of water release.
• 4. Sensor check: If pressure is correct but E9 persists, the flow or temperature sensors may be misreading and should be tested and replaced if necessary.