Glow-worm EnergySaver 50P Fault codes & diagnostics

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

Regular LPG 1993-2002 Discontinued
GC Number 41-319-73
Download the Glow-worm EnergySaver 50P manualThe official installation and service manual (PDF). 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 →

Fault codes

All 1 documented codes

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APS neon lit

Your boiler has detected an issue with the airflow system, which is preventing the burner from lighting for safety reasons.

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

Parts commonly replaced

  • Air Pressure Switch
  • Fan Assembly
  • Venturi Tube
Full explanation for APS neon lit
Status & diagnostic codes

12 operating states & engineer diagnostics

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

4.5 Diagnostic Your boiler is struggling to maintain the correct internal pressure required to safely burn the gas needed to heat your home. 8.79 Diagnostic This code is not actually an error, but a technical display showing the boiler's current power output level while it is operating normally. 10.16 Diagnostic Your boiler is displaying a technical system parameter rather than a breakdown error, usually indicating a configuration or communication issue between internal components. 11.8 Diagnostic Your boiler is detecting an issue with the gas pressure being supplied to the burner, which prevents it from heating your water or home safely. 14.3 Diagnostic Your boiler has detected an issue with the internal gas pressure regulation, meaning it cannot safely control the size of the flame required to heat your home. 14.65 Diagnostic Your boiler is currently performing a diagnostic check to confirm its heating output levels and is not experiencing a functional fault. 16.12 Diagnostic Your boiler is currently performing a routine self-check of its heating power output and is not reporting an active fault. 16.94 Diagnostic Your boiler is displaying a technical information code rather than a fault, indicating the system is reporting its power settings to the display. 17.0 Diagnostic Your boiler has detected an incorrect internal gas pressure, which means it cannot safely ignite or heat your water. 17.58 Diagnostic Your boiler is displaying a status message indicating the current heating power level it is operating at, rather than reporting a system fault. 18.64 Diagnostic Your boiler is displaying a technical configuration code that indicates it is not currently set up to operate correctly for your home. 20.33 Diagnostic Your boiler is displaying a technical system information code rather than a fault, which usually occurs when the unit has been recently installed or had its settings adjusted.