BoilerFaultCodesThe 5 most common faults
01
é1 High DIY-safe
Your boiler has reached an unsafely high internal temperature, likely because there is not enough water flowing through the system to carry the heat away.
What to try first
Check the boiler pressure gauge and top it up to 1.5 bar using the filling loop if it is too low.Ensure all radiator valves are fully open and not turned off.Bleed all radiators to remove trapped air which may be blocking water flow.Reset the boiler by pressing the reset button for two seconds.
02
é2 High DIY-safe
Your boiler has stopped working because water is not moving through the system properly or there is too much air trapped inside.
What to try first
Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Bleed all radiators to remove trapped air that might be blocking water flow.Ensure all radiator valves and any isolation valves under the boiler are fully open.
03
E1 High Engineer
Your boiler has detected a fault with the internal thermometer that monitors water temperature, causing the system to shut down for safety.
Full guide for E104
é0 High Engineer
Your boiler has detected a problem with its internal temperature sensors, which means it cannot monitor heat levels safely and has stopped working.
Full guide for é005
e45 High Engineer
Your boiler's internal computer has lost its saved settings and is no longer communicating correctly with its own components.
Full guide for e45on the Remeha Avanta Plus 28c
Circulation PumpFlow/Return Temperature Sensor (NTC)Main Heat Exchanger (Cleaning/Descaling)Flow/Return temperature sensors (NTC)Circulation pumpAutomatic air vent
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 Remeha 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