BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water pressure is either too low or too high for it to operate safely, or the sensor that monitors this pressure has lost its connection.
Check the pressure gauge on the front of the boiler or via the digital display.If the pressure is below 1.0 bar, use the filling loop valves to carefully top up the system to 1.5 bar.If the pressure is above 3.0 bar, bleed a radiator to release excess water and pressure.Reset the boiler once the pressure is within the normal operating range (1.0 to 1.5 bar).
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Ensure all radiator valves are fully open to allow water to flow.Check that the boiler pressure gauge is between 1.0 and 1.5 bar; top up if it is too low.Press the Reset button once the boiler has had 30 minutes to cool down.
Your boiler has detected that water is not circulating properly through the system, which could be due to trapped air, low pressure, or a blockage.
Check the pressure gauge and top up to 1.5 bar if it is lowBleed all radiators to remove trapped air from the systemEnsure all radiator valves and isolation valves under the boiler are fully open
Your boiler has stopped working because the water pressure is too low and the system needs to be topped up.
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Open the one or two taps/levers on the loop slowly until you hear water entering.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps fully.
Your boiler has stopped working because it cannot detect the water pump running or there is a lack of water circulation to maintain safe operation.
Check the pressure gauge is between 1.0 and 1.5 bar; top up using the filling loop if it is too low.Ensure all radiator valves and boiler isolation valves are fully open.Try resetting the boiler by pressing the 'Reset' button once the pressure is corrected.
Your boiler is failing to light properly, meaning it cannot produce heat or hot water because the burner is not firing up.
Check that your gas pre-payment meter is in creditEnsure other gas appliances in your home are working to confirm gas supplyReset the boiler by pressing the reset button for 2-3 seconds
on the Atag iS System
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