BoilerFaultCodesThe 6 most common faults
Your boiler's internal communication system is confused because two or more parts are trying to use the same digital identification signal.
Identify all wall-mounted or wireless thermostats connected to your heating system.Check the configuration settings on each thermostat to ensure they are assigned unique zone addresses.Restart the boiler and your thermostat(s) to allow them to re-establish a conflict-free connection.
Your boiler is having trouble 'talking' to its wireless thermostat, meaning it cannot receive signals to turn the heating or hot water on.
Check that your wireless thermostat controller has fresh batteries installedTurn the boiler off at the fused spur for 60 seconds and then turn it back on to reset the connectionEnsure there are no new large metal objects or electronic devices placed between the boiler and the thermostat that could block the signal
Your boiler's computer system has detected a minor internal processing error that is preventing it from operating correctly.
Switch the boiler off at the fused spur or mains power for 60 secondsTurn the power back onUse the control panel to reset the current time and date according to your user manual
Your boiler has detected that the water pressure inside the system has risen too high, causing it to shut down for safety.
Locate the external filling loop, which is a silver braided hose connecting two pipes near the boiler.Ensure both valves on the filling loop are firmly closed to stop more water from entering the system.Bleed one or two radiators in the house to release excess water pressure until the boiler's pressure gauge drops back into the green zone.
Your boiler has stopped working because the amount of water circulating inside the system has dropped below the required level.
Locate the filling loop (a metal braided hose) situated underneath the boiler.Open the valves on the filling loop slowly until you hear water flowing.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).Close both valves firmly and ensure the boiler resets.
Your boiler is not detecting enough air flow to safely release exhaust gases, so it has shut itself down to prevent a hazard.
Locate the external filling loop (a flexible metal or braided hose) connected to the underside of the boiler or nearby pipeworkSlowly open the valve(s) on the filling loop to allow water into the system until the pressure gauge reads between 1.0 and 1.5 barClose the valve(s) tightly and restart the boiler to see if the fault clears
on the Navien NCM 1130HH
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 Navien 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