Glow-worm Hideaway 100CFF Fault codes & diagnostics

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

Regular Natural Gas 2002-present
GC Number 41-047-42
Download the Glow-worm Hideaway 100CFF manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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.
7 High
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
41-047-42 Hideaway 100CFF 2002–present

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

Fault codes

All 7 documented codes

Tap any card for details

Electrical Fault Finding

Your boiler is not receiving the electrical power it needs to start, likely because the external clock or thermostat is not sending a signal to turn it on.

High DIY-safe £80-150

What to check first

  1. Check your thermostat and make sure it is set to a temperature higher than the current room temperature.
  2. Verify that your heating programmer or timer display is active and set to 'On' for the current time.
  3. Check your home's fuse box or consumer unit to ensure the boiler's circuit breaker has not tripped.

Parts commonly replaced

  • External programmer
  • Room thermostat
  • Fused spur
  • Wiring centre
Full explanation for Electrical Fault Finding
Electrical Supply Failure

Your boiler has stopped working because it has lost its electricity supply, but it should restart automatically once the power is back on.

High DIY-safe

What to check first

  1. Check your home's main fuse box (consumer unit) to ensure no circuit breakers have tripped.
  2. Verify that the fused spur switch feeding the boiler is in the 'on' position.
  3. Turn the boiler temperature control to '0', wait 30 seconds, then turn it fully clockwise to 'Max' to trigger a reset.

Parts commonly replaced

  • Fused spur switch
  • Internal wiring harness
  • Printed circuit board
Full explanation for Electrical Supply Failure
NEON5

Your boiler has switched itself off because it has detected that the water inside has become dangerously hot.

High DIY-safe £90-220

What to check first

  1. Wait for the boiler to cool down completely (at least 20-30 minutes).
  2. Locate the reset button, typically found behind the small drop-down door or on the underside of the boiler.
  3. Press the reset button firmly; if the neon light goes out and the boiler restarts, monitor it closely.
  4. Ensure all radiator valves are open and the pump is running to prevent it happening again.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Thermistor

Related codes

Full explanation for NEON5
Neon6

Your boiler has stopped working because it failed to light or stay lit when it was supposed to.

High DIY-safe £120-280

What to check first

  1. Turn the temperature control knob to the 'Off' position
  2. Wait for at least 30 seconds for the unit to reset
  3. Turn the temperature control knob back to your desired setting
  4. Ensure there is gas reaching the property (check other gas appliances)

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame sensing probe
  • PCB

Related codes

Full explanation for Neon6
Pilot Fault Finding

Your boiler's small starter flame will not stay lit, meaning the device cannot safely ignite the main burner to provide heat or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Pilot burner assembly
  • Gas valve
  • Pilot supply pipe
Full explanation for Pilot Fault Finding
Reset neon

Your boiler has safety-tripped and needs a manual restart to clear a temporary glitch or overheating issue.

High DIY-safe £0-120

What to check first

  1. Turn the boiler temperature control knob to '0' (the off position).
  2. Wait for at least 30 seconds for the internal components to reset.
  3. Turn the knob back to your desired temperature setting and follow standard lighting procedures.

Parts commonly replaced

  • Overheat Thermostat
  • Thermocouple
  • Fan
Full explanation for Reset neon
Reset neon lights

Your boiler has safety-tripped and simply needs a manual restart to try and fire up again.

High DIY-safe £0-120

What to check first

  1. Turn the boiler temperature control knob to the '0' position.
  2. Wait for at least 30 seconds.
  3. Turn the control knob back to your desired temperature setting to restart the ignition sequence.

Parts commonly replaced

  • Overheat Thermostat
  • Ignition Electrode
  • Gas Valve
Full explanation for Reset neon lights
Status & diagnostic codes

4 operating states & engineer diagnostics

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

NEON1 Status This light simply indicates that the boiler is receiving power and is switched on at the wall or spur. NEON2 Status Your boiler is receiving a signal to provide heat or hot water, which typically means it is operating as normal. NEON3 Status Your boiler has detected that the internal fan is spinning, but it hasn't received the signal to proceed with the next step of the ignition process. NEON4 Status Your boiler is currently operating normally and the burner is ignited as it should be to provide heat.
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