BoilerFaultCodesIdeal 34 Fault Code
The Ideal 34 fault code means: your boiler has detected that gas is potentially still flowing or a flame signal is present when it should be turned off, which is a safety concern.. It appears on 1 Ideal model in our database.
Technical description: Gas valves do not close; check the voltage on the gas valve. If a voltage is measured on both the gas valves (> 20 V), the control panel should be replaced. When ionisation occurs while the unit is not operational, the ionisation circuit should be checked. If the control panel and the ionisation function properly, the gas valve has to be replaced.
What causes the Ideal 34 fault?
This fault occurs when the boiler's internal sensors detect a flame or gas flow even after the system has been told to shut down. The most common reasons are a gas valve that is physically stuck open or a control board that is incorrectly sending power to the valve when it shouldn't. It can also be caused by a faulty sensor that is 'seeing' a flame that isn't actually there.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ideal models that show the 34 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 34 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026