BoilerFaultCodes.com

Vaillant ecoTEC Fault Codes

CombiSystemRegular Natural GasLPG 12-38 kW 2005-present
GC Numbers: 47-044-3247-044-3347-044-3447-044-3547-044-3647-044-3747-044-3847-044-3947-044-4047-044-4147-044-4247-044-4347-044-4447-044-4547-044-4647-044-4747-044-4847-044-4947-044-5047-044-5147-044-5247-044-6447-044-6547-044-6641-044-4441-044-4541-044-4641-044-4741-044-4841-044-4941-044-5041-044-5141-044-5241-044-5341-044-5441-044-5541-044-63

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Most common fault codes

con
Your boiler's internal computer screen and main control board are having trouble talking to each other, meaning the unit cannot function.
Gas Safe engineer required · £150-£450
D,11
Your boiler is struggling to push hot water around your radiators because an external pump is not responding correctly.
Gas Safe engineer required · £180-350
F.0
Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, causing it to stop running as a safety precaution.
Gas Safe engineer required · £90-160

All 33 fault codes

Code Severity Plain English
con High Your boiler's internal computer screen and main control board are having trouble talking to each other, meaning the unit cannot function.
D,11 High Your boiler is struggling to push hot water around your radiators because an external pump is not responding correctly.
F.0 High Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, causing it to stop running as a safety precaution.
F.1 High Your boiler has stopped working because one of its internal temperature sensors has lost connection or failed.
F.10 High Your boiler has stopped working because one of its internal sensors has developed an electrical fault and can no longer measure the temperature of the water leaving the unit.
F.11 High Your boiler has detected an electrical fault with the sensor that monitors water returning from your radiators, causing the system to shut down for safety.
F.13 High Your boiler has detected an electrical fault with the sensor that monitors your hot water tank temperature, preventing it from heating your water correctly.
F.20 High Your boiler has switched itself off because it has detected that the water inside is getting too hot.
F.22 High Your boiler has stopped working because the water pressure is too low for it to run safely.
F.23 High Your boiler is struggling to move water around the system properly, causing it to overheat and shut down for safety.
F.24 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.
F.25 High Your boiler has detected an electrical connection issue or a sudden temperature rise, causing it to shut down for safety.
F.27 High Your boiler's safety system is detecting a flame when there shouldn't be one, or the sensor that monitors the flame has developed a fault.
F.28 High Your boiler is not receiving gas or is unable to light a flame to provide heating and hot water.
F.29 High Your boiler has lost its flame while running and is now unable to relight itself to provide heat or hot water.
F.32 High Your boiler has detected an issue with the air fan, meaning it cannot safely circulate the air and gas needed to stay lit.
F.49 High Your boiler has lost communication with its external controls, such as your thermostat, often due to an electrical wiring error or interference.
F.61 High Your boiler has detected an electrical communication problem with the gas valve, which is preventing it from lighting safely.
F.62 Emergency Your boiler has detected a potential safety issue where the gas valve is not closing properly or the control board is misreading the gas flow.
F.63 High Your boiler's internal computer brain has developed a memory error and can no longer process the information it needs to run safely.
F.64 High Your boiler has detected an electrical fault or a sensor failure and has shut down as a safety precaution.
F.65 High Your boiler’s internal computer has overheated, causing it to shut down to prevent permanent damage.
F.67 High Your boiler's internal computer has detected an electrical fault with the flame sensor and has shut down for safety.
F.70 High Your boiler's internal computer parts have lost their identity settings or been replaced incorrectly, meaning the system can no longer communicate with itself to operate.
F.71 High Your boiler has detected that a temperature sensor is stuck or faulty, meaning it cannot accurately monitor the water temperature to operate safely.
F.72 High Your boiler’s temperature sensors are giving conflicting readings, causing the system to shut down to prevent overheating.
F.73 High Your boiler has lost the ability to monitor its own water pressure due to a sensor or wiring fault, causing the system to shut down for safety.
F.74 High Your boiler is struggling to read its internal water pressure correctly because of a technical glitch in the sensor or its wiring.
F.75 High Your boiler is unable to detect a change in water pressure when the pump starts up, preventing it from firing up for heating or hot water.
F.76 High Your boiler has shut down because a safety sensor has detected that the main heating component is getting too hot or has a broken internal fuse.
F.77 High Your boiler has shut down because it is unable to drain away the waste water it produces, or a safety sensor on the flue system has been triggered.
F.78 High Your boiler is confused because it is trying to communicate with an external control box that isn't compatible with its current setup.
F70 High Your boiler's computer parts are not communicating correctly because they haven't been told which specific model of boiler they are installed in.

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
D.0 Diagnostic Your boiler is currently restricted to a lower power setting for heating, meaning your radiators might take longer to warm up or may not get as hot as they should.
D.1 Diagnostic Your boiler is not broken; it is simply continuing to run the internal pump for a few minutes to safely cool down the heat exchanger after providing heating or hot water.
D.2 Diagnostic Your boiler is temporarily resting because it has reached its target temperature and is waiting for a short period before restarting to prevent unnecessary wear and tear.
D.3 Diagnostic Your boiler is currently showing you the live temperature of the hot water it is producing, which is a normal status message rather than an error.
D.4 Diagnostic Your boiler is currently showing the live temperature reading of the sensor responsible for keeping your hot water pre-heated.
D.5 Diagnostic Your boiler is displaying a status message to show the temperature it is currently trying to reach for your heating or hot water, rather than being a functional fault code.
D.7 Diagnostic Your boiler is displaying an information code to show that the pre-heated water feature for your taps is currently active.
D.8 Diagnostic Your boiler is receiving a signal from your thermostat or external controls asking for heat, and it is operating as it should.
D.9 Diagnostic Your boiler is receiving a instruction to heat water to a specific temperature from an external thermostat or smart heating control.
D.10 Diagnostic Your boiler's internal pump is having trouble circulating water through the system, which is preventing your heating from working.
D.12 Diagnostic Your boiler is having trouble communicating with the pump that heats your hot water cylinder, meaning you may experience a lack of hot water.
D.13 Diagnostic Your boiler is having trouble moving hot water through the internal pipes, which usually means the circulation pump cannot start or is stuck.
D.14 Diagnostic Your boiler is struggling to control the speed of its internal pump, meaning water may not be circulating through your radiators efficiently.
D.15 Diagnostic Your boiler is displaying an information code because the pump that moves water around your pipes is spinning at a different speed than expected.
D.17 Diagnostic Your boiler has switched its control method to the return pipe because it is detecting a potential issue with the main flow sensor.
D.18 Diagnostic Your boiler is currently set to run the pump continuously, which is usually a configuration setting rather than a breakdown.
D.20 Diagnostic Your boiler has reached the maximum allowed temperature for heating your hot water cylinder and is pausing operation as a standard safety limit.
D.22 Diagnostic Your boiler is currently providing hot water to your taps or shower, which is a normal status message rather than an actual fault.
D.23 Diagnostic Your boiler is currently set to summer mode, which means it is only heating your tap water and has temporarily turned off the central heating.
D.24 Diagnostic Your boiler is struggling with water flow, likely due to a build-up of debris or air in the system which is preventing the heat from circulating properly.
D.25 Diagnostic Your boiler is currently busy heating your hot water because your smart thermostat or external controller has told it to do so.
D.26 Diagnostic Your boiler's internal control board is unable to communicate with an optional secondary accessory or pump, causing the system to stop running as a safety precaution.
D.27 Diagnostic Your boiler's internal control board is having trouble communicating with an external part or accessory, which may prevent the system from starting up correctly.
D.28 Diagnostic Your boiler is having trouble communicating with an external control or smart home accessory, which might prevent your heating or hot water from turning on correctly.
D.30 Diagnostic Your boiler is struggling to send the correct message to its gas supply valves, which usually means it cannot light safely.
D.33 Diagnostic Your boiler is struggling to match the correct fan speed needed to safely clear exhaust gases, which may lead to the system pausing for safety.
D.34 Diagnostic Your boiler is struggling to accurately measure how fast its internal fan is spinning, which is preventing the system from heating correctly.
D.35 Diagnostic Your boiler is currently switching over between its heating and hot water functions.
D.40 Diagnostic Your boiler is displaying the temperature it is currently aiming for rather than a fault, which is a normal status message and not a breakdown.
D.41 Diagnostic Your boiler is displaying the current temperature of the water returning from your radiators rather than indicating a fault.
D.44 Diagnostic Your boiler's electronic system is struggling to correctly detect the flame signal, which could lead to it locking out for safety.
D.47 Diagnostic Your boiler's outside temperature sensor is either giving an incorrect reading or has lost communication with the main control system.
D.50 Diagnostic This is a technical status message indicating the boiler is adjusting its fan speed settings and is not usually a hardware fault.
D.51 Diagnostic Your boiler is flagging a minor technical adjustment error regarding its internal fan speed settings.
D.60 Diagnostic Your boiler has shut down multiple times because it reached a dangerously high temperature and is recording how often this safety limit has been triggered.
D.61 Diagnostic Your boiler is recording that it has repeatedly failed to light or stay on, leading to multiple safety shutdowns.
D.64 Diagnostic Your boiler is taking longer than usual to light, though it is still currently working.
D.65 Diagnostic Your boiler is struggling to spark or light the gas correctly, which is a safety mechanism preventing it from trying to ignite for too long.
D.67 Diagnostic Your boiler is simply taking a short, programmed break between heating cycles to protect its internal parts and operate more efficiently.
D.68 Diagnostic Your boiler is struggling to light its flame on the first try, though it may eventually start after several attempts.
D.69 Diagnostic Your boiler has failed to light the flame twice in a row, which means the system has stopped working for your safety.
D.70 Diagnostic Your boiler is currently stuck in a diagnostic test mode that overrides its normal settings, which usually happens during a service or repair.
D.71 Diagnostic Your boiler is currently set to run at its maximum possible heating temperature, meaning it is working as hard as it can to heat your radiators.
D.72 Diagnostic Your boiler is continuing to run its internal pump for a short period after heating your water to ensure it cools down safely and efficiently.
D.75 Diagnostic Your boiler is taking longer than expected to heat up your hot water tank, causing the system to stop as a precaution.
D.76 Diagnostic Your boiler is taking a short, programmed break to prevent itself from turning on and off too frequently, which protects the internal components from unnecessary wear.
D.77 Diagnostic Your boiler is temporarily reducing its power while heating your hot water cylinder because it is reaching its temperature limit too quickly.
D.78 Diagnostic Your boiler is limiting the temperature of the water being sent to your hot water cylinder, which typically means the water won't get as hot as usual.
D.80 Diagnostic This is not a fault; it is simply a diagnostic screen displaying how many hours your boiler has spent running the central heating.
D.81 Diagnostic This is an information code rather than a fault, showing you the total number of hours your boiler has spent heating up your water.
D.82 Diagnostic Your boiler is currently checking its systems and preparing to fire up the burner to provide central heating.
D.83 Diagnostic Your boiler is providing a status update to show it is currently heating up the water for your taps.
D.84 Diagnostic Your boiler is simply letting you know that it is due for its routine annual service soon.
D.90 Diagnostic Your boiler is currently waiting for the digital control system to finish communicating, which usually means it is temporarily busy rather than broken.
D.91 Diagnostic Your boiler is checking for a radio signal to automatically set the time and date using an outdoor weather sensor.
D.93 Diagnostic Your boiler's internal computer has lost its identity settings and doesn't know which specific model it is supposed to be.
D.96 Diagnostic Your boiler has reverted to its original factory settings and needs its specific configuration data entered to work correctly with your heating system.
D.97 Diagnostic Your boiler is currently showing a hidden menu used by engineers for advanced system analysis, but it does not represent an actual mechanical fault.
D.98 Diagnostic This is a prompt or status message indicating that the boiler requires professional maintenance or has reached a specific service interval that needs an engineer's attention.
S.0 Status Your boiler is working perfectly; it is simply in standby mode because your heating and hot water are currently at the temperatures you have set.
S.1 Status Your boiler is simply going through its normal startup sequence by circulating water before it attempts to ignite.
S.3 Status Your boiler is currently trying to light the flame to start your central heating.
S.4 Status Your boiler is currently operating normally and the burner has successfully lit to provide heat or hot water.
S.6 Status Your boiler is briefly cooling down internal components after it has stopped heating your water or radiators.
S.7 Status Your boiler is temporarily running the pump to cool itself down after a period of activity, which is a normal operation rather than a fault.
S.8 Status Your boiler is taking a short, normal break to prevent the system from switching on and off too frequently after it has finished heating your home.
S.10 Status Your boiler has detected that you have turned on a hot water tap and is currently working to heat water for you.
S.14 Status Your boiler is operating normally and is currently in the process of starting up the burner to provide heat or hot water.
S.20 Status Your boiler is simply letting you know it is currently busy heatng up your hot water tank or keeping its internal water reserve warm.
S.24 Status Your boiler is temporarily reducing its power because it has reached the required temperature and is waiting for the heat to be distributed before firing up again normally.
S.30 Status Your boiler is working correctly but is currently in standby because your thermostat or programmer is not asking it to provide any heat.
S.31 Status Your boiler is currently set to summer mode, which means it will provide hot water to your taps but will not turn on your central heating radiators.
S.34 Status Your boiler has detected very cold temperatures and has turned itself on automatically to prevent the internal pipes from freezing.

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