BoilerFaultCodes BURNER LIT NEON
Your boiler is operating normally and the flame is successfully lit to provide your heating or hot water.
Halstead Hero Fault codes & diagnostics
14 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 24-28 kW 2006-2012 Discontinued
Replaced by: ACE
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 8 High
6 Low
Just want the most common Halstead Hero faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 14 documented codes
Tap any card for details
BURNER ON
Your boiler is currently trying to ignite and is working exactly as it should to start supplying your heating and hot water.
DEMAND NEON
Your boiler is working correctly and is currently receiving a request from your thermostat or taps to provide heating or hot water.
FAN NEON
The indicator light is showing that your boiler's internal ventilation fan is active, which is a normal part of the startup and shutdown sequence.
FLAME FAILURE NEON Your boiler has stopped working because it cannot light the gas burner or keep it burning.
Your boiler has stopped working because it cannot light the gas burner or keep it burning.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner assembly
- PCB
Related codes
LOCK OUT Your boiler has stopped working for safety reasons and needs a manual reset to attempt to start up again.
Your boiler has stopped working for safety reasons and needs a manual reset to attempt to start up again.
What to check first
- Turn your boiler thermostat dial fully anti-clockwise to the reset position and hold it there for a few seconds.
- Turn the dial clockwise back to your desired temperature setting.
- Wait a few minutes to see if the boiler ignites and the flame icon appears.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Printed circuit board (PCB)
Related codes
Neon L1 Your boiler is connected to the electricity supply and is waiting for a request to provide heating or hot water, so everything is working exactly as it should.
Your boiler is connected to the electricity supply and is waiting for a request to provide heating or hot water, so everything is working exactly as it should.
What to check first
- No action is required as this is the normal standby light
- Turn on your central heating or hot water at the programmer
- Check your thermostat settings to ensure heat is requested
Neon L2 Your boiler is struggling to correctly read or communicate the temperature of the water, so it has safely paused operation to prevent overheating.
Your boiler is struggling to correctly read or communicate the temperature of the water, so it has safely paused operation to prevent overheating.
Parts commonly replaced
- NTC Thermistor
- Printed Circuit Board (PCB)
Related codes
Neon L3 Your boiler is struggling to clear exhaust fumes because it cannot confirm that the internal fan is moving air properly, preventing it from lighting safely.
Your boiler is struggling to clear exhaust fumes because it cannot confirm that the internal fan is moving air properly, preventing it from lighting safely.
Parts commonly replaced
- Air Pressure Switch
- Flue Fan
- Venturi
Neon L4 Your boiler is failing to detect a flame, so it has purposefully shut itself down to prevent a gas leak.
Your boiler is failing to detect a flame, so it has purposefully shut itself down to prevent a gas leak.
Parts commonly replaced
- Flame rectification electrode
- Ignition lead
- Printed Circuit Board (PCB)
Neon L5 Your boiler has detected an electrical fault involving a blown internal safety fuse, which is preventing the system from operating.
Your boiler has detected an electrical fault involving a blown internal safety fuse, which is preventing the system from operating.
Parts commonly replaced
- Internal PCB fuse
- Control PCB
Related codes
Neon L6 Your boiler has stopped working because it failed to light the burners or keep them running, and it needs a manual reset to try again.
Your boiler has stopped working because it failed to light the burners or keep them running, and it needs a manual reset to try again.
Parts commonly replaced
- Ignition electrode
- Flame rectification sensor
- Gas valve
Related codes
OVERHEAT NEON Your boiler has automatically shut itself down because it detected that it is getting too hot, likely due to a circulation problem.
Your boiler has automatically shut itself down because it detected that it is getting too hot, likely due to a circulation problem.
Parts commonly replaced
- Overheat thermostat
- Central heating pump
- PCB
STANDBY NEON Your boiler is perfectly fine and is simply waiting for you to turn on a tap or adjust your heating thermostat.
Your boiler is perfectly fine and is simply waiting for you to turn on a tap or adjust your heating thermostat.
What to check first
- Check your room thermostat is set higher than the current room temperature
- Ensure your heating timer or programmer is set to 'on'
- Run a hot water tap to see if the boiler fires up