BoilerFaultCodesThe 6 most common faults
01
13 High DIY-safe
Your boiler is not receiving any electrical power, so the main power light remains off and the unit cannot start.
What to try first
Check if your home's main electrical consumer unit has a tripped circuit breaker.Ensure the boiler's fused spur switch (usually near the boiler) is turned on.Check if your external room thermostat or programmer is set to 'On' and has power.Check the fuse in the boiler's power switch (only if comfortable changing a standard plug-style fuse).
02
L E High Engineer
Your boiler's electronic command center has detected an internal error and has stopped working to prevent further damage.
Full guide for L E03
L A High Engineer
Your boiler has detected that it is running too hot and has automatically switched itself off to prevent damage.
Full guide for L A04
H E High Engineer
Your boiler has detected an internal computer error, meaning its 'brain' is failing to communicate properly and it cannot safely run.
Full guide for H E05
Neon I1 High Engineer
Your boiler is failing to start because it detects that the internal fan system is not operating correctly, likely due to a sensor incorrectly reporting air pressure levels before the system has even begun to run.
Full guide for Neon I106
Neon I3 Low DIY-safe
Your boiler is receiving power and is currently in its normal standby state, meaning it is ready to fire up whenever you turn on your heating or hot water.
What to try first
No action is required as this is a normal operating status lightCheck your thermostat settings if you were expecting the heating to be on
on the Ideal Classic NF30–NF80
External fuseInternal PCB fuseControl ProgrammerWiring harnessPrinted Circuit Board (PCB)Overheat thermostat
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 Ideal 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