Halstead Hero Fault codes & diagnostics

4 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Regular Natural Gas 24-28 kW 2006-2012 Discontinued
GC Numbers 41-260-0441-260-0541-260-0641-260-0741-260-08

Replaced by: ACE

Choose your boiler type

The Hero range comes in 3 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

30 0 codes · 1 GC number 40 0 codes · 1 GC number 50 0 codes · 1 GC number
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

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 4 documented codes

Tap any card for details

FLAME FAILURE NEON

Your boiler has stopped working because it cannot light the gas burner or keep it burning.

High Engineer only £120-250 Shared across the Hero range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Burner assembly
  • PCB

Related codes

Full explanation for FLAME FAILURE NEON
LOCK OUT

Your boiler has stopped working for safety reasons and needs a manual reset to attempt to start up again.

High DIY-safe £100-250 Shared across the Hero range

What to check first

  1. Turn your boiler thermostat dial fully anti-clockwise to the reset position and hold it there for a few seconds.
  2. Turn the dial clockwise back to your desired temperature setting.
  3. 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

Full explanation for LOCK OUT
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.

High Engineer only £120-250 Shared across the Hero range

Parts commonly replaced

  • Ignition electrode
  • Flame rectification sensor
  • Gas valve

Related codes

Full explanation for Neon L6
OVERHEAT NEON

Your boiler has automatically shut itself down because it detected that it is getting too hot, likely due to a circulation problem.

High Engineer only £120-250 Shared across the Hero range

Parts commonly replaced

  • Overheat thermostat
  • Central heating pump
  • PCB
Full explanation for OVERHEAT NEON
Status & diagnostic codes

10 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

BURNER LIT NEON Status Your boiler is operating normally and the flame is successfully lit to provide your heating or hot water. BURNER ON Status Your boiler is currently trying to ignite and is working exactly as it should to start supplying your heating and hot water. DEMAND NEON Status Your boiler is working correctly and is currently receiving a request from your thermostat or taps to provide heating or hot water. FAN NEON Status 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. Neon L1 Status 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. Neon L2 Status Your boiler is struggling to correctly read or communicate the temperature of the water, so it has safely paused operation to prevent overheating. Neon L3 Status 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. Neon L4 Status Your boiler is failing to detect a flame, so it has purposefully shut itself down to prevent a gas leak. Neon L5 Status Your boiler has detected an electrical fault involving a blown internal safety fuse, which is preventing the system from operating. STANDBY NEON Status Your boiler is perfectly fine and is simply waiting for you to turn on a tap or adjust your heating thermostat.