BoilerFaultCodesGlow-worm Red flashing light Fault Code
Also written as REDFLASHINGLIGHT — same fault.
The Glow-worm Red flashing light fault code means: your boiler has encountered a general operation error and needs to be restarted to resume heating and hot water.. It appears on 2 Glow-worm models in our database.
Technical description: Fault occurred. Reset boiler: Turn the On/Off switch to ( 0 ), wait for five seconds. Turn the On/Off switch to ( I ) the boiler is reset.
What causes the Glow-worm Red flashing light fault?
This fault occurs when the boiler's internal computer detects an interruption in the normal operating sequence, causing it to shut down for safety. The most common reasons include a failure to sense a flame correctly or a momentary communication error between the electronic components. If the reset doesn't work, it usually indicates that a part like the ignition lead or the main circuit board is failing to send the correct signals.
DIY fix possible
Locate the On/Off switch on the boiler control panelTurn the switch to the '0' positionWait for five secondsTurn the switch back to the 'I' position to reset the unit
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Gas Safe Register →Glow-worm models that show the Red flashing light fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm Red flashing light fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026