BoilerFaultCodesThe 6 most common faults
Your boiler has automatically stopped working because the water pressure inside your heating system has dropped too low.
Locate the two small valves (filling loop) connected to the pipework underneath your boiler.Slowly open the valves to allow mains water into the system while watching the pressure gauge on the front of the boiler.Once the needle reaches the green zone (typically between 1.0 and 1.5 bar), tightly close both valves.
Your boiler has detected that the water pressure inside your heating system is too high and has safely shut itself down to prevent damage.
Locate a radiator in your home, preferably one upstairs.Using a radiator bleed key, open the bleed valve slightly to let a small amount of water out into a container.Monitor the pressure gauge on the front of your boiler until it drops back into the green zone (typically between 1.0 and 1.5 bar), then tightly close the radiator bleed valve.
Your boiler has detected that an external safety device, such as a heat sensor or chimney flue thermostat, has triggered a shutdown to prevent overheating or unsafe operation.
Full guide for Block 01Your boiler's internal settings have been incorrectly configured, preventing it from safely regulating its power output.
Full guide for Block 60Your boiler has automatically paused itself because the waste gases exiting the flue are dangerously hot, likely indicating an internal system blockage or a failed sensor.
Full guide for Block 80Your boiler has detected that a critical safety sensor monitoring exhaust gases has become unplugged or disconnected, so it has safely shut itself down to prevent operation.
Full guide for Block 81on the Atag Q 25CR
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Atag shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue