BoilerFaultCodesYour boiler has become too hot and has automatically shut itself down to prevent damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat thermostat operated
What causes this fault?
This fault occurs when the internal water temperature exceeds a safe limit, causing the boiler to shut down for safety. The most common reasons are a pump failure that stops water from moving or a blockage in the system pipes that prevents heat from being carried away from the boiler quickly enough.
This issue is more frequent during the first cold snap of autumn when a pump that has been idle all summer suddenly seizes or struggles to circulate water through the radiators.
DIY fix possible
Wait for the boiler to cool down completely for at least 30 minutes.Check that your radiator valves are open and not turned off.Locate the reset button on the control panel and press it firmly to restart the unit.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E02 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Potterton Envoy 30 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.