BoilerFaultCodes.com

Vaillant ecoTEC exclusive Fault Codes

CombiSystem Natural GasLPG 27-43 kW 2016-present
GC Numbers: 47-044-6347-044-6441-044-84

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Most common fault codes

con
Your boiler's internal computer brain is unable to talk to the front display panel, meaning the system cannot receive instructions to provide heating or hot water.
Gas Safe engineer required · £180-450
F.0
Your boiler has lost its connection to the sensor that measures the water temperature as it leaves the unit, meaning it cannot safely judge how much heat to provide.
Gas Safe engineer required · £90-180
F.1
Your boiler has stopped working because it cannot communicate with the sensor that monitors the temperature of the water returning to the unit.
Gas Safe engineer required · £90-180

All 35 fault codes

Code Severity Plain English
con High Your boiler's internal computer brain is unable to talk to the front display panel, meaning the system cannot receive instructions to provide heating or hot water.
F.0 High Your boiler has lost its connection to the sensor that measures the water temperature as it leaves the unit, meaning it cannot safely judge how much heat to provide.
F.1 High Your boiler has stopped working because it cannot communicate with the sensor that monitors the temperature of the water returning to the unit.
F.10 High Your boiler has stopped working because it thinks the main water temperature sensor is broken or there is a problem with its internal wiring.
F.11 High Your boiler has stopped working because it cannot correctly read the temperature of the water returning to the unit due to an electrical connection issue.
F.13 High Your boiler has detected an electrical fault with the internal sensor that monitors the temperature of its hot water storage tank.
F.20 High Your boiler has shut down because it has detected an unsafe increase in internal temperature, likely caused by a sensor fault or an issue with water flow.
F.22 High Your boiler has stopped working because the water pressure is too low for it to operate safely.
F.23 High Your boiler has detected that water isn't moving through the system fast enough, causing a large temperature difference that has triggered a safety shutdown.
F.24 High Your boiler is overheating too quickly because water isn't flowing through the system correctly, often due to low pressure or trapped air.
F.25 High Your boiler has detected an internal electrical connection issue that is preventing it from running safely.
F.27 High Your boiler has detected a flame when there shouldn't be one, which has caused the system to shut down for safety.
F.28 High Your boiler is failing to light the gas flame, meaning it cannot provide heat or hot water.
F.29 High Your boiler has lost its flame while running and cannot manage to restart itself, likely due to a temporary interruption in the gas supply or a component failure.
F.32 High Your boiler has detected a problem with the fan that safely pushes waste gases out of your home, causing the system to shut down for safety.
F.49 High There is a communication error between your boiler and its controls, often caused by an electrical wiring fault or a heavy load on the internal data connection.
F.61 High Your boiler has detected a technical communication error between the main control board and the gas valve, preventing it from lighting safely.
F.62 Emergency Your boiler has detected a potential internal gas leak or an electrical failure that stops the gas supply from closing correctly, so it has shut down for safety.
F.63 High Your boiler's internal computer brain has developed a memory error and can no longer process instructions correctly.
F.64 High Your boiler has detected an electrical fault within its internal sensors or control board, which has caused the system to shut down for safety.
F.65 High Your boiler’s internal computer brain is overheating, which has caused the system to shut down for safety.
F.67 High Your boiler's main control board is receiving an incorrect electrical signal from the flame sensor, meaning the system cannot safely confirm if the burner is lit.
F.70 High Your boiler’s internal computer boards are having trouble communicating because they haven't been properly synced or configured to recognize each other.
F.71 High Your boiler has detected that a temperature sensor is sending a stuck or frozen reading, preventing it from heating your home or water safely.
F.72 High Your boiler has detected that its temperature sensors are giving conflicting or incorrect readings, causing it to shut down for safety.
F.73 High Your boiler's internal sensor that monitors water pressure has lost electrical contact or has failed, causing the system to stop working for safety.
F.74 High Your boiler has detected an electrical issue with its internal water pressure sensor, meaning it cannot accurately tell if there is enough water in the system to run safely.
F.75 High Your boiler has stopped working because it cannot detect the necessary change in pressure when the pump starts up.
F.76 High Your boiler has detected a safety-related electrical fault within its internal wiring or a heat protection fuse, causing it to shut down to prevent damage.
F.77 High Your boiler is struggling to remove excess water or is experiencing a communication error with an external safety part, causing it to shut down to prevent damage.
P.0 Low Your boiler is currently running a self-cleaning routine to remove trapped air bubbles from your pipes and radiators.
P.1 Low Your boiler is currently running a self-test at maximum power to ensure everything is working correctly after it has started up.
P.2 Low Your boiler is currently running a background test to check that it is burning gas correctly at its lowest possible setting.
P.5 Low Your boiler is currently running a programmed self-test to check that it can safely shut down if it gets too hot.
P.6 Low Your boiler is currently running a maintenance program to help fill or drain the system, meaning it has temporarily paused its normal heating and hot water functions.

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.0 Status Your boiler is working perfectly; it is simply in standby mode because your thermostat hasn't asked it to turn on for heating or hot water yet.
S.1 Status Your boiler is currently preparing to start the fan as part of its normal ignition process.
S.2 Status Your boiler is currently warming itself up and checking that water is flowing correctly before it starts heating your home.
S.3 Status Your boiler is currently going through its starting sequence and is trying to ignite the flame to provide heating or hot water.
S.4 Status Your boiler is operating normally and is currently in the process of heating your home or water.
S.5 Status Your boiler is pausing briefly because it has finished its heating cycle or has reached the required temperature and is now cooling down internal components.
S.6 Status Your boiler has paused its operation because it is not receiving the correct feedback signal from the fan that pushes exhaust gases out of the system.
S.7 Status Your boiler is temporarily pausing because it has detected that water is returning to the unit too quickly or at an unexpected temperature.
S.8 Status Your boiler is taking a mandatory cooling break to prevent overheating after a period of intense work.
S.10 Status Your boiler has detected that you have turned on a hot water tap and is currently working to provide hot water to your home.
S.11 Status Your boiler is currently preparing to fire up by starting its internal fan, which is a normal part of the ignition process.
S.13 Status Your boiler is struggling to light its flame, which means you may experience intermittent issues with your heating and hot water.
S.14 Status Your boiler is currently operating normally and is in the process of burning gas to provide heating or hot water.
S.15 Status Your boiler is performing a self-check to ensure water is moving correctly and the fan is working before it attempts to ignite.
S.16 Status Your boiler has detected an issue with the air fan system and has temporarily stopped heating to prevent further damage.
S.17 Status Your boiler has detected that the water is not flowing correctly through the heating system, likely because a valve is closed or there is a blockage.
S.20 Status Your boiler is not broken; it is simply letting you know it is currently busy heating up your hot water cylinder or keeping its internal hot water supply ready for use.
S.21 Status Your boiler is currently going through its normal starting sequence to begin heating your water.
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 currently operating normally and is in the process of heating your radiators.
S.25 Status Your boiler is pausing briefly to check the water flow and fan speed are working correctly before it tries to fire up.
S.26 Status Your boiler's fan is attempting to spin, but the electronic control board isn't receiving the correct signal back to confirm it is working properly.
S.27 Status Your boiler has sensed water moving in the wrong direction or at the wrong pressure near the pump, which is preventing it from heating your home properly.
S.28 Status Your boiler is temporarily pausing its heating cycle to prevent it from switching on and off too frequently after a short period of use.
S.30 Status Your thermostat has told the boiler to stay switched off because your home has reached the requested temperature or a timer has kicked in.
S.31 Status Your boiler is currently set to its summer setting or is being told by your thermostat not to turn on the heating because it thinks the house is warm enough.
S.32 Status Your boiler has temporarily paused operation because it detected unusual airflow that could lead to freezing or a fan issue.
S.34 Status Your boiler has noticed the temperature is very cold and has automatically turned itself on to prevent the internal pipes from freezing.
S.36 Status Your temperature settings are too low for the boiler to start heating, so the system is currently on standby.
S.41 Status Your boiler has too much water in the system, which is causing high pressure and has triggered a safety shutdown to protect the components.
S.42 Status Your boiler has paused operation because it cannot safely clear waste gases or discharge wastewater produced during the heating process.
S.53 Status Your boiler has temporarily paused because the water is not flowing through the system fast enough, causing it to heat up too quickly.
S.54 Status Your boiler has temporarily paused itself because it detected that the water temperature is rising too quickly, suggesting there isn't enough water circulating through the system.
S.96 Status Your boiler is performing a self-diagnostic check on its internal temperature sensors and has temporarily paused heating until it confirms everything is working correctly.
S.97 Status Your boiler is currently performing a self-test of its internal pressure sensor and has temporarily paused heating until it finishes.
S.98 Status Your boiler is temporarily pausing to double-check that its internal temperature sensors are reading correctly before it starts heating your home.

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