BoilerFaultCodesIdeal F 0t Fault Code
Also written as F0T — same fault.
The Ideal F 0t fault code means: your boiler is having trouble communicating with your wall thermostat, meaning it doesn't know when to turn your heating on or off.. It appears on 3 Ideal models in our database.
Technical description: Room Thermostat Fault: Check Room Stat & connections
What causes the Ideal F 0t fault?
This fault occurs when the boiler loses its physical or wireless connection to the wall thermostat, leaving it unable to receive an instruction to start. The most common reasons are dead batteries in the room thermostat or a loose wire in the terminal block where the controls connect to the boiler. In some cases, it can be caused by signal interference or a hardware failure within the thermostat unit itself.
This fault is often noticed during the first cold spell of autumn when homeowners try to turn their heating back on after a long summer of inactivity.
DIY fix possible
Check if your room thermostat is switched on and hasn't run out of batteries.Ensure the thermostat is set to a temperature higher than the current room temperature.If using a wireless thermostat, check that the receiver next to the boiler is showing power and try re-pairing the device.
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Gas Safe Register →Ideal models that show the F 0t fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal F 0t 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