Your boiler has detected a signal error between its control system and gas supply, preventing it from lighting safely.

No demand to gas valve | Cause: Electronic board defective, Gas valve defective

What causes this fault?

This fault occurs when the boiler's internal computer detects a flame signal at a time when there shouldn't be one, or if the sensors are providing conflicting information. The most common reason is a communication failure between the electronic control board and the gas valve, causing the system to shut down as a safety precaution. In some cases, moisture or a failing component can trick the boiler into thinking gas is burning when the valve is actually closed.