BoilerFaultCodes.com

Saunier Duval Isotwin Condens Fault Codes

Combi Natural GasLPG 30-35 kW 2010-present

All 50 fault codes

Code Severity Plain English
F1 High Your boiler has failed to light the gas flame despite several attempts, causing the system to shut down for safety.
F1,  F4, High Your boiler has failed to ignite, which means it cannot heat up to provide warmth or hot water for your home.
F1, F4 High Your boiler is unable to safely light the flame needed to provide heating and hot water.
F4 High Your boiler is failing to stay lit or cannot start the flame required to provide heating and hot water.
F5 High Your boiler has switched itself off because it has reached an unsafe temperature to protect the internal components from damage.
F5 High Your boiler has switched itself off because it has become too hot internally and needs to cool down for safety.
F5 High Your boiler has switched itself off because it has become too hot inside the internal pipework.
F6 High Your boiler has detected a problem with the sensor that monitors the temperature of the water heading to your radiators, causing the system to shut down for safety.
F6 High Your boiler has detected a problem with the sensor that monitors the temperature of the water used to heat your radiators, causing the system to stop working for safety.
F6,F7, High Your boiler has detected a communication or electrical fault with the sensors that monitor the temperature for your heating and hot water, meaning it cannot operate safely.
F7 High Your boiler has detected a problem with the sensor that monitors hot water temperature, which typically means you will have little or no hot water.
F8 High Your boiler's temperature sensor for the hot water storage tank has developed a fault, meaning the system cannot safely monitor or heat your hot water.
F9 High Your boiler has detected an issue with the sensor that monitors water pressure, which means it cannot verify if there is enough water to run safely.
F9 High Your boiler has detected an issue with the sensor that monitors internal water pressure, causing the system to stop working for safety.
F10 High Your boiler has detected a problem with the sensor that monitors the temperature of the water returning to the unit, which has caused the heating to stop working.
F10 High Your boiler has detected an issue with the sensor that monitors the temperature of the water returning from your radiators, preventing it from heating your home safely.
F10 High Your boiler has detected an issue with the sensor that monitors the temperature of the water returning from your radiators, preventing it from heating your home safely.
F11 High Your boiler is having trouble communicating with its control panel, which means it isn't receiving the instructions it needs to provide heating or hot water.
F11 High Your boiler's main control panel is having trouble communicating with its internal computer, meaning your commands aren't reaching the heating system.
F11 High Your boiler's internal computer is having trouble communicating with the other parts of the system, preventing it from starting up correctly.
F12 High Your boiler's internal computer has lost communication with the control panel or display, preventing the system from operating.
F12 High Your boiler's control panel is having trouble communicating with the main internal computer, meaning settings cannot be adjusted and the unit may stop running.
F13 High Your boiler's internal computer has lost communication with its electronic components and needs a professional reset or repair.
F13 High Your boiler's internal computer has lost communication with its electronic components and can no longer control the heating process.
F13 High Your boiler's internal computer brain is having trouble communicating with the main circuitry, causing the system to stop working.
F14 High Your boiler has shut down because the water inside the central heating system has reached an unsafely high temperature.
F14 High Your boiler has sensed that the water inside is getting too hot and has shut down as a safety precaution.
F16 Emergency Your boiler is still detecting a flame even after it has been told to turn off, which is a safety concern that requires a professional inspection.
F16 Emergency Your boiler is still detecting a flame even though it has been told to turn off, which is a safety concern that requires a professional inspection.
F16 Emergency The boiler is detecting a flame even though it has commanded the system to turn off, which may indicate a faulty sensor or a valve that isn't closing fully.
F17 High Your boiler has stopped working because the electrical power coming from your home's mains supply is too low for it to run safely.
F17 High Your boiler has stopped working because the electrical voltage coming from your mains power supply has dropped too low for the system to operate safely.
F18 High Your boiler's control panel and the internal computer are having trouble communicating with each other, meaning the display may not work or respond to your commands.
F18 Medium Your boiler's control panel has stopped communicating properly with the main system, meaning you cannot adjust settings or see current status.
F18 High Your boiler's control panel and the internal computer are failing to communicate with each other.
F19 High Your boiler has lost its connection to the sensor that monitors heating temperature, so it has stopped running as a safety precaution.
F19 High Your boiler has lost its connection to the sensor that monitors the temperature of the water in your radiators.
F19 High Your boiler has lost its connection to the temperature sensor that controls the central heating, meaning it cannot tell how hot the water is and has shut down as a safety precaution.
F20 High Your boiler's internal computer parts are having trouble communicating with each other, causing the system to shut down for safety.
F20 High Your boiler's computer parts are not speaking the same language and cannot communicate with each other properly.
F20 High Your boiler's internal computer chips are having trouble communicating with each other, causing the system to shut down for safety.
F23 High Your boiler has sensed that water is not moving through the system properly, which is causing it to shut down to prevent overheating.
F23 High Your boiler is struggling to move water through the system, which is causing it to shut down to prevent overheating.
F24 High Your boiler has stopped working because the water returning from your radiators has become too hot, which usually means the water isn't circulating properly through the system.
F25 High Your boiler has detected that the water temperature is rising too quickly, which usually means the water isn't flowing through the system properly.
F26 High Your boiler has detected that the water is getting hot too quickly or the temperature difference between pipes is too wide, often caused by poor water flow.
F26 High Your boiler has sensed that the water leaving the unit is much hotter than the water returning, meaning heat isn't moving through your system properly.
F26 High Your boiler has shut down because it is heating up too quickly or there is a lack of water flow, often caused by a blockage or a pump issue.
F28 High Your boiler has detected that its temperature sensors are giving conflicting readings, which has caused it to stop working for safety.
F29 High Your boiler has shut down because a safety component has detected that the internal temperature reached a level high enough to potentially damage the system.

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