BoilerFaultCodes.com

Glow-worm Ultracom 24cx 30cx Fault Codes

Combi Natural GasLPG 24-30 kW 2007-2011 Discontinued
GC Numbers: 47-019-0347-019-04

Replaced by: Ultracom2 cxi

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Most common fault codes

-9OC
Your boiler has detected a problem with the sensor that monitors hot water temperature, likely due to a loose connection or a fault in the internal wiring.
Gas Safe engineer required · £90-160
F
Your boiler has encountered a general operation error that is usually caused by a sudden interruption to the gas or electricity supply.
May be DIY safe · £80-220
F00
Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit.
Gas Safe engineer required · £90-160

All 34 fault codes

Code Severity Plain English
-9OC High Your boiler has detected a problem with the sensor that monitors hot water temperature, likely due to a loose connection or a fault in the internal wiring.
F High Your boiler has encountered a general operation error that is usually caused by a sudden interruption to the gas or electricity supply.
F00 High Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit.
F1 High Your boiler has failed to ignite and has shut itself down for safety, meaning you will not have any heating or hot water until it is reset or repaired.
F01 High Your boiler has stopped working because a sensor that monitors the temperature of the water returning from your radiators has developed a fault.
F5 High Your boiler has switched itself off for safety because it has reached an excessively high temperature, likely due to a circulation problem.
F10 High Your boiler has detected a problem with the sensor that measures the temperature of the water leaving the unit, causing it to shut down as a safety precaution.
F11 High Your boiler has detected an issue with the sensor that monitors the temperature of the water coming back from your radiators, preventing it from heating your home safely.
F12 High Your boiler has lost communication with the sensor that monitors the temperature of your hot water cylinder, meaning it cannot heat your water correctly.
F13 Medium Your boiler's hot water sensor has developed a technical fault, preventing the system from accurately measuring and heating your water.
F20 High Your boiler has switched itself off to prevent damage because the internal water temperature has become too hot.
F22 High Your boiler has detected that the water pressure is too low to operate safely and has shut down to prevent damage.
F23 High Your boiler has stopped working because the water isn't moving through the system fast enough, causing the internal temperature to rise too quickly.
F24 High Your boiler is heating up too quickly because water isn't flowing through the system properly, causing it to shut down to prevent overheating.
F25 High Your boiler has switched itself off because the internal exhaust gases have reached a temperature that is too high, often caused by a circulation problem or a lack of water.
F26 High Your boiler has detected a problem with how gas is flowing into the system, which means it cannot light safely and has shut down as a precaution.
F27 High Your boiler has sensed a flame when there shouldn't be one, or the sensor that monitors the fire is sending a confusing signal to the control board.
F28 High Your boiler is failing to light the gas flame, which means your heating and hot water will not work until the system is reset or repaired.
F29 High Your boiler has lit successfully but then lost its flame while it was running, causing the system to shut down for safety.
F43 High Your boiler has lost its memory of whether it is a 24kW or 30kW model, meaning it cannot operate safely until its settings are re-programmed.
F49 High Your boiler has lost communication with its external controls like your thermostat because there is an electrical problem with the wiring connecting them.
F61 High Your boiler has detected an internal communication failure between the main control board and the gas valve, meaning it cannot safely light the flame.
F62 High Your boiler has detected an internal electronics failure that prevents it from safely controlling the gas supply, meaning it has shut down for safety.
F63 High Your boiler's internal computer brain has developed a memory error and can no longer process its instructions correctly.
F64 High Your boiler’s internal computer brains are struggling to talk to each other, meaning the system cannot run safely.
F65 High Your boiler's internal computer boards are having trouble communicating with each other, preventing the system from starting up.
F67 High Your boiler's internal computer boards have stopped communicating correctly, meaning the system cannot process commands or operate safely.
F70 High Your boiler's main control board has lost communication with its internal identity chip, effectively meaning the boiler has forgotten which model it is and cannot operate.
F72 High Your boiler is struggling to accurately measure the water temperature, causing it to shut down to prevent overheating.
F73 High Your boiler is struggling to read its own water level because of an electrical sensor issue, which has caused it to stop working as a safety precaution.
F74 High Your boiler is having trouble measuring how much water is inside the system, which is causing it to stop running for safety.
F75 High Your boiler has stopped working because it cannot detect the necessary change in water pressure required to safely start the heating process.
F77 High Your boiler has detected an issue with the system that removes waste water or measured a temperature imbalance, causing it to shut down as a safety precaution.
F81 High Your boiler is struggling to heat up water for your taps because the internal pump or sensor that manages hot water is not working correctly.

Status & diagnostic codes

These codes indicate your boiler's operating state or a diagnostic reading — not necessarily a fault. Status codes (S.) mean normal operation; diagnostic codes (D.) are informational readings used by engineers.

Code Type Description
S.00 Status Your boiler is working correctly and is currently in standby mode because your thermostat has reached the desired temperature or the heating timer is off.
S.01 Status Your boiler is preparing to start the heating process by running the internal fan to clear out the combustion chamber.
S.02 Status Your boiler is performing a routine start-up check by running the internal pump for a few moments before lighting the burner.
S.03 Status Your boiler is currently attempting to light the flame but is failing to do so, meaning you won't have heating or hot water until it succeeds.
S.04 Status Your boiler is working normally and is currently firing up to provide hot water for your taps or showers.
S.05 Status Your boiler is temporarily cooling itself down after finishing a heating or hot water cycle, which is a normal part of its operation.
S.06 Status Your boiler's fan is continuing to run after it should have stopped, causing the system to pause for safety reasons.
S.07 Status Your boiler is continuing to run its internal water pump after the heating or hot water has been turned off to safely cool down the heat exchanger.
S.08 Status Your boiler is taking a short, programmed break to prevent it from turning on and off too frequently, which helps save energy and protect its internal parts.
S.10 Status Your boiler is simply letting you know that someone has turned on a hot tap and it is currently busy heating water for your shower or sink.
S.11 Status Your boiler is performing a routine start-up check by running the internal fan before the burner ignites.
S.13 Status Your boiler is currently struggling to light the flame it needs to provide heating and hot water.
S.14 Status Your boiler is not showing an error; it is simply displaying a status message to let you know that the burner is currently active and heating your water.
S.15 Status Your boiler is continuing to run its internal components after the heating or hot water has been turned off to safely cool down the system.
S.16 Status Your boiler's fan is running longer than necessary to clear out exhaust gases, which may temporarily stall the start-up process.
S.17 Status Your boiler is continuing to run its internal pump after the heating or hot water has turned off to help cool down the internal components.
S.20 Status Your boiler is temporarily pre-heating the internal water to ensure you get hot water quickly when you turn on a tap.
S.21 Status Your boiler is performing a routine start-up check by running its internal fan before lighting the burner.
S.22 Status Your boiler is performing a routine check of the internal pump to ensure water is flowing correctly before it starts the main heating process.
S.23 Status Your boiler is currently struggling to light the flame it needs to provide heating and hot water.
S.24 Status Your boiler is operating normally; this is a status message indicating that the burner is currently lit and heating your water.
S.25 Status Your boiler is staying in a cooling-down mode because it thinks the internal temperature is still too high after the heating or hot water has turned off.
S.26 Status Your boiler's fan is staying on longer than it should after the heating or hot water has been turned off.
S.27 Status Your boiler is continuing to run the pump for a short period after the heating has switched off to safely move excess heat away from the internal components.
S.28 Status Your boiler is taking a short, programmed break to prevent it from turning on and off too frequently, which protects the internal parts from unnecessary wear.
S.30 Status Your boiler is working fine but hasn't started the heating because your external thermostat or timer is currently telling it to stay off.
S.31 Status Your boiler is currently set to provide hot water only, and the central heating has been disabled because it is in summer mode.
S.32 Status Your boiler has temporarily paused operation because it has detected very cold temperatures or an unusual fluctuation in the fan speed, often caused by strong winds or a blocked flue.
S.34 Status Your boiler is not broken; it has simply noticed the temperature is very low and is running briefly to prevent the internal pipes from freezing.
S.36 Status Your boiler is working fine, but your external thermostat or programmer isn't telling it to turn the heating on.
S.42 Status Your boiler has paused its heating process because an external control or smart accessory is preventing it from firing up.
S.53 Status Your boiler has temporarily paused because the water temperature is rising too quickly or unevenly, suggesting a circulation issue or a sensor fault.
S.54 Status Your boiler has sensed that there isn't enough water moving through the system to heat up safely, so it has shut down to protect itself.
S.76 Status Your boiler has paused because it is waiting for a stable reading from the internal water pressure sensor.
S.96 Status Your boiler is temporarily pausing to perform a routine check on its internal temperature sensors before it can provide heating or hot water.
S.97 Status Your boiler is temporarily pausing to check the system's water pressure before it starts up to provide heating or hot water.
S.98 Status Your boiler is temporarily pausing because it has detected a suspicious temperature difference and is double-checking that its heat sensors are working correctly before it continues.

Glow-worm Ultracom 24cx 30cx 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.

UK's #1 online installer
Boxt
Fixed-price online quotes. Next-day installation.
Get a free quote →
Heatable
Instant online boiler quotes from £1,499.
Get a free quote →
iHeat
Fast installation. Price match guarantee.
Get a free quote →

Affiliate links — we may earn a commission at no extra cost to you.