BoilerFaultCodesIdeal Boiler Overheat Thermostat Fault Code
Also written as BOILEROVERHEATTHERMOSTAT — same fault.
The Ideal Boiler Overheat Thermostat fault code means: your boiler has switched itself off because it got too hot, and it needs to cool down before it can be restarted.. It appears on 3 Ideal models in our database.
Technical description: Safety cutout thermostat will extinguish the pilot and shut down the boiler in the event of overheating. Requires manual reset via button (E) after the boiler has cooled.
What causes the Ideal Boiler Overheat Thermostat fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety switch to shut everything down. The most common reasons are a failed pump that isn't moving water away from the boiler quickly enough or a blockage in the system pipework. It can also happen if the main control thermostat fails and allows the burner to stay on for too long.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after being idle all summer, which can cause the internal pump to seize.
DIY fix possible
Wait at least 15-20 minutes for the boiler to cool down naturally.Locate the manual reset button (marked E) on the control panel.Press the button firmly and attempt to relight the pilot light following the instructions on the boiler's flap.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ideal models that show the Boiler Overheat Thermostat fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal Boiler Overheat Thermostat 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