Glow-worm Hideaway 100 Fault codes & diagnostics

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

Regular Natural Gas 29.3 kW Discontinued

This boiler uses indicator light combinations

Note which lights are on, off, or flashing and at what speed. Match the combination to the cards below. Do not reset until you have noted the pattern. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
9 High 4 Low
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The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 13 documented codes

Tap any card for details

LED / flash-pattern codes
Indicator 1 (Reset) Lit

Your boiler has switched itself off as a safety precaution because it has either detected a fault or has become too hot.

High DIY-safe £100-250

What to check first

  1. Locate the reset button on the control panel.
  2. Press and release the reset button to see if the boiler restarts.
  3. Check that your heating controls (thermostat) are calling for heat.
  4. Ensure your gas supply is active and hasn't been interrupted.

Parts commonly replaced

  • Overheat Thermostat
  • PCB (Printed Circuit Board)
  • Pump
Full explanation for Indicator 1 (Reset) Lit
Indicator: Reset/Standby lit

Your boiler has switched itself off because it has either gotten too hot or it failed to light the flame correctly.

High DIY-safe £120-280

What to check first

  1. Check that your gas supply is turned on at the meter
  2. Ensure all radiator valves are open and there is water in the system
  3. Press the reset button on the front control panel to see if the boiler restarts

Parts commonly replaced

  • Overheat Thermostat
  • Ignition Electrode
  • Gas Valve
  • Circulation Pump
Full explanation for Indicator: Reset/Standby lit
Simultaneous 1 Slow / 1 Fast

Your boiler is failing to start because its internal safety checks haven't confirmed that the fan is pushing waste gases out of the flue correctly.

High Engineer only £120-£350

Parts commonly replaced

  • Fan Assembly
  • Air Pressure Switch
  • Venturi Tube
Full explanation for Simultaneous 1 Slow / 1 Fast
Digital codes
Burner On neon going out

Your boiler is failing to detect its own flame correctly, causing it to shut down shortly after trying to start.

High Engineer only £120-250

Parts commonly replaced

  • Flame supervision electrode
  • Ignition lead
  • Gas valve
  • Printed Circuit Board (PCB)
Full explanation for Burner On neon going out
NEON1

This light simply indicates that the boiler is receiving power and is switched on at the wall or spur.

Low DIY-safe

What to check first

  1. No action required as this is a status indicator, not a fault
  2. If the boiler is not firing despite this light being on, check that your thermostat is turned up
  3. Ensure your programmer is set to 'ON' or 'AUTO'

Related codes

Full explanation for NEON1
NEON2

Your boiler is receiving a signal to provide heat or hot water, which typically means it is operating as normal.

Low DIY-safe

What to check first

  1. Check your room thermostat is set to the desired temperature
  2. Ensure your programmer or heating timer is switched to 'On'
  3. Wait for the boiler to complete its startup cycle as this light indicates normal operation

Related codes

Full explanation for NEON2
NEON3

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.

High Engineer only £120-280

Parts commonly replaced

  • Air Pressure Switch
  • Venturi Tube
  • Fan Assembly

Related codes

Full explanation for NEON3
NEON4

Your boiler is currently operating normally and the burner is ignited as it should be to provide heat.

Low DIY-safe

What to check first

  1. No action is required as this is a status indicator, not an error.
  2. Ensure your thermostat is set to the desired temperature.
  3. Check that your programmer is set to an 'on' period.

Related codes

Full explanation for NEON4
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
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