BoilerFaultCodes.com

Glow-worm 18si 24ci Fault Codes

CombiSystem Natural GasLPG 18-24 kW 2003-2006 Discontinued
GC Numbers: 41-047-6647-047-23

Replaced by: Flexicom

This boiler uses indicator light combinations

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

Most common fault codes

0.5bar
Your boiler has lost water pressure and has shut down to prevent damage, meaning you will not have any heating or hot water until the system is topped up.
May be DIY safe · £0-120
01
Your boiler has stopped working because it cannot light the gas flame or it can't detect that the flame is lit.
May be DIY safe · £100-280
02
Your boiler has detected an issue with its internal ventilation system, meaning it cannot safely clear waste gases and has shut down as a precaution.
Gas Safe engineer required · £120-£350

All 22 fault codes

Code Severity Plain English
0.5bar High Your boiler has lost water pressure and has shut down to prevent damage, meaning you will not have any heating or hot water until the system is topped up.
01 High Your boiler has stopped working because it cannot light the gas flame or it can't detect that the flame is lit.
02 High Your boiler has detected an issue with its internal ventilation system, meaning it cannot safely clear waste gases and has shut down as a precaution.
2.7bar Emergency Your boiler has too much water inside it, causing the internal pressure to rise to an unsafe level.
05 High Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
06 High Your boiler has detected a problem with the sensor that measures the temperature of the water going to your radiators, causing the system to stop working for safety.
09 High Your boiler has lost track of the system's water pressure because a sensing part has stopped working properly.
11 High Your boiler's internal display screen is unable to communicate with its main control computer, preventing the boiler from firing up.
12 High Your boiler's main control screens are having trouble talking to each other, which means the boiler doesn't know what settings you are asking for.
13 High Your boiler's internal computer has developed a fault and can no longer control the heating and hot water functions safely.
14 High Your boiler has become too hot and has shut down as a safety precaution to prevent damage.
15 High Your boiler is unable to control the flow of gas required for ignition, meaning it cannot light to provide heat or hot water.
16 High Your boiler has detected a problem with the internal gas valve and has shut down as a safety precaution, meaning you will have no heating or hot water.
17 High Your boiler is receiving too little electricity from the mains supply to operate safely, causing it to shut down.
18 High Your boiler's control panel has lost communication with the main computer, meaning you cannot adjust settings or operate the unit.
19 High Your boiler has stopped working because its internal temperature sensor has lost contact with the pipework or is failing to send a signal.
20 High Your boiler's internal control screen is unable to communicate properly with the main computer board, often after a recent repair or parts change.
F1 High Your boiler is trying to start up but cannot detect a flame, causing the system to shut down for safety.
F4 High Your boiler is lighting up but quickly switching itself off because it cannot confirm that a flame is safely present.
Red flashing boiler ON indicator High Your boiler has detected that the water pressure is too low for it to operate safely and has shut down as a precaution.
Red flashing light High Your boiler has encountered a general operation error and needs to be restarted to resume heating and hot water.
Red flashing running lamp High Your boiler has lost water pressure and has shut down as a safety precaution.

Glow-worm 18si 24ci is discontinued — time for a new one?

Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.

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