BoilerFaultCodesIdeal Room Thermostat Fault Fault Code
Also written as ROOMTHERMOSTATFAULT — same fault.
The Ideal Room Thermostat Fault fault code means: your boiler has lost communication with your heating controls, meaning your radiators might not turn on when you want them to.. It appears on 5 Ideal models in our database.
Technical description: Check room thermostat batteries
What causes the Ideal Room Thermostat Fault fault?
This fault occurs when the boiler is unable to receive a signal from your heating controls, meaning it doesn't know whether it should be heating your home or not. The most common reason is that the batteries in your wall-mounted thermostat have run out of power, though it can also happen if the wireless signal is being blocked by a new obstacle or if the receiver on the boiler itself has developed a fault.
This fault is frequently seen at the start of autumn when homeowners turn their heating back on for the first time and discover their thermostat batteries have drained over the summer.
DIY fix possible
Locate your wall-mounted room thermostat or portable controllerOpen the battery compartment (usually by sliding a cover or pressing a small tab)Replace the old batteries with a brand new set of high-quality alkaline batteriesCheck if the display on the thermostat turns back on and try to call for heat
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Gas Safe Register →Ideal models that show the Room Thermostat Fault fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal Room Thermostat Fault 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