Vaillant ecoTEC Pro / ecoTEC Plus System Fault codes & diagnostics

5 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

System Natural GasLPG 24-38 kW 2005-present

Download the Vaillant ecoTEC Pro / ecoTEC Plus System manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

The fault code is already on your display

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

Just want the most common Vaillant ecoTEC Pro / ecoTEC Plus System faults?

The top 6 problems in plain English — with causes, DIY checks and repair costs.

Fault codes

All 5 documented codes

Tap any card for details

What to check first

Check if other gas appliances, like a hob, are still working to ensure your gas supply hasn't been interrupted.
If it is freezing outside, check the condensate pipe (the plastic pipe leading outside) for ice and defrost it with warm water.
Press the reset button (a flame symbol with a cross through it) for five seconds to see if the boiler restarts.

Parts commonly replaced

Ignition Electrode
Gas Valve
Flame Sensing Electrode
PCB

Related codes

F.28

Parts commonly replaced

Gas valve
Gas valve wiring harness
PCB

Related codes

Parts commonly replaced

actoSTOR sensor
Wiring harness

Related codes

Parts commonly replaced

Gas valve
Printed Circuit Board (PCB)
Wiring harness

Related codes

Parts commonly replaced

Gas valve
Printed Circuit Board (PCB)
Wiring harness

Related codes

Status & diagnostic codes

75 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

D.000 Diagnostic This code is not actually an error; it simply displays the current heating power setting that your boiler is using to warm your home. D.001 Diagnostic This is a normal operational status message indicating that your boiler is circulating water to safely cool down after the heating has been running. D.002 Diagnostic Your boiler is currently in a mandatory waiting period to prevent it from turning on and off too frequently, which is a normal protective feature. D.003 Diagnostic Your boiler is simply reporting the current temperature of the water flowing out of it, and this code is usually just an information message rather than an actual fault. D.004 Diagnostic Your boiler is struggling to detect the temperature of the water inside your hot water cylinder, which may result in your water not heating up properly. D.005 Diagnostic Your boiler is simply displaying the current temperature it has been told to reach for your radiators, so everything is working exactly as it should. D.006 Diagnostic Your boiler is currently monitoring its internal temperature settings and is waiting for the system to reach the required heat level. D.007 Diagnostic Your boiler is simply displaying the internal temperature setting currently being used for its hot water storage, rather than reporting an actual fault or system error. D.008 Diagnostic Your boiler's internal control system is having difficulty communicating with its main command centre, which is preventing the boiler from firing up as requested. D.009 Diagnostic Your boiler is struggling to communicate correctly with your thermostat or external heating control unit. D.010 Diagnostic Your boiler is having trouble detecting the water pump, which means it cannot circulate heat to your radiators or taps. D.011 Diagnostic Your boiler has detected that the device responsible for pushing water around your heating system is not responding correctly. D.012 Diagnostic Your boiler is struggling to pump hot water into your hot water cylinder, which means your taps or shower may not get warm. D.013 Diagnostic Your boiler is struggling to move water through your heating system, which means it cannot circulate heat to your radiators or taps. D.014 Diagnostic Your boiler is currently monitoring its internal water circulation speed, which is a normal part of its automatic operation and usually does not indicate a fault. D.015 Diagnostic Your boiler is reporting a communication issue regarding the speed at which your internal water pump is running. D.016 Diagnostic Your boiler is currently receiving a signal to provide heating, and this code is simply an internal status update confirming that your system's controls are successfully requesting warmth. D.017 Diagnostic Your boiler has detected an internal communication mismatch between its internal settings and the connected control components, meaning it does not know how to correctly manage the heating system. D.018 Diagnostic Your boiler is simply displaying a status message indicating that the internal water pump is currently running to move heat around your home. D.019 Diagnostic This code is simply an information display showing the current speed setting of your boiler's internal water pump, not a fault with your heating system. D.020 Diagnostic Your boiler is currently monitoring or adjusting the maximum temperature limit for your hot water supply as part of its normal internal operation. D.022 Diagnostic Your boiler has received a signal requesting hot water and is currently preparing to heat it for your taps. D.023 Diagnostic This code is not actually an error, but a simple status update indicating that your boiler is currently waiting because the heating system has reached its target temperature. D.025 Diagnostic Your boiler is currently focused on heating your hot water storage tank, which is a normal part of its routine operation. D.026 Diagnostic Your boiler is having trouble communicating with an external accessory, like a smart thermostat or a pump controller, preventing it from heating your home properly. D.027 Diagnostic Your boiler is having trouble communicating with an external add-on component, such as a heating pump or an external control device. D.028 Diagnostic Your boiler has detected an issue with an external device connected to it, such as a heating pump or an external water tank controller. D.029 Diagnostic Your boiler is struggling to detect enough water flowing through the system to operate safely. D.033 Diagnostic Your boiler is struggling to reach the required fan speed to safely clear exhaust gases, which is preventing it from starting up properly. D.034 Diagnostic Your boiler is struggling to confirm that the internal fan is spinning at the correct speed, which prevents the unit from starting safely. D.035 Diagnostic Your boiler is struggling to switch between heating your radiators and heating your hot water, which usually means a mechanical part inside is stuck. D.036 Diagnostic Your boiler is struggling to detect the flow of hot water, which means it may not be able to provide consistent hot water to your taps or shower. D.039 Diagnostic Your boiler is receiving an unusual temperature reading from the solar water heating connection, likely due to a faulty sensor or loose wiring. D.040 Diagnostic Your boiler is simply reporting the current temperature of the water flowing through your heating system, which is normal operational information rather than a fault. D.041 Diagnostic Your boiler is struggling to accurately measure the temperature of the water returning from your radiators to the heating system. D.044 Diagnostic Your boiler is struggling to detect the flame correctly during the ignition process, which is preventing it from heating your water or home. D.046 Diagnostic Your boiler is currently running a self-diagnostic test on the water pump to ensure it is circulating heat correctly. D.047 Diagnostic Your boiler is receiving an unusual signal from the sensor that measures the air temperature outside your home. D.050 Diagnostic Your boiler's internal computer is reporting an issue with the settings that control the minimum speed of the fan, which is preventing the system from operating correctly. D.051 Diagnostic Your boiler is struggling to correctly control the speed of its internal fan, which is preventing it from starting up or operating properly. D.058 Diagnostic Your boiler is currently drawing heat from your solar thermal system to boost your hot water, which is a normal operational status rather than a fault. D.060 Diagnostic Your boiler has detected that it is getting too hot and has turned itself off multiple times to prevent damage, indicating a potential blockage in your heating system or a failing pump. D.061 Diagnostic Your boiler has detected that it failed to light the flame too many times in a row and has temporarily locked itself out for safety. D.064 Diagnostic Your boiler is noting that the time it takes to successfully light the flame is slightly longer than normal, indicating a potential struggle to start up. D.065 Diagnostic Your boiler is failing to light because it cannot detect a flame within the required time, meaning you currently have no heating or hot water. D.067 Diagnostic Your boiler is currently in a brief, automatic waiting period between heating cycles to prevent excessive wear and tear. D.068 Diagnostic Your boiler is currently monitoring how many attempts it has made to start up, which usually happens during a standard diagnostic cycle or a minor temporary glitch. D.069 Diagnostic Your boiler is struggling to ignite and has needed several attempts to start up successfully. D.070 Diagnostic Your boiler is struggling to switch between heating your radiators and heating your hot water, which may result in one of those functions not working correctly. D.071 Diagnostic Your boiler has detected that the water temperature is higher than the limit set by your heating controls. D.072 Diagnostic Your boiler is simply moving residual heat away from your hot water tank to ensure the system cools down safely after a heating cycle. D.073 Diagnostic Your boiler's internal sensor is detecting a slight temperature difference compared to what it expects, which is essentially a communication glitch. D.074 Diagnostic Your boiler is currently running a routine, automated high-temperature cycle to kill off any potential bacteria in your hot water tank. D.075 Diagnostic Your boiler has stopped trying to heat your hot water tank because it has been running for too long without reaching the target temperature. D.076 Diagnostic Your boiler has detected an issue with its internal identification software or configuration settings, meaning it cannot communicate correctly with its own internal systems. D.077 Diagnostic Your boiler is currently running at a lower power setting than normal for heating your tap water, which is an informational status rather than an active fault. D.078 Diagnostic Your boiler is temporarily limiting the temperature of your hot water because it has detected that the water leaving the heater is hotter than the system expects. D.080 Diagnostic This code is simply an information display showing the total number of hours your boiler has spent actively heating your home. D.081 Diagnostic This code is simply an information display showing the total number of hours your boiler has spent heating your hot water, rather than indicating a fault with the system. D.082 Diagnostic Your boiler is simply performing a routine safety check on the burner ignition system, which is a normal part of its startup process. D.083 Diagnostic This is a normal operational message indicating your boiler is currently starting up to heat your hot water. D.084 Diagnostic Your boiler is reminding you that it is due for its annual safety service to ensure it continues to run efficiently and safely. D.088 Diagnostic Your boiler is struggling to detect the flow of water needed to provide hot water to your taps. D.090 Diagnostic Your boiler is having trouble communicating with its external controls, such as your thermostat or programmer, preventing it from receiving instructions on when to turn the heating on. D.091 Diagnostic Your boiler is currently trying to synchronize its internal clock with a radio signal from a time transmitter, which is a normal process and not a fault. D.092 Diagnostic Your boiler is having trouble talking to your hot water storage tank, which may cause issues with your hot water supply. D.093 Diagnostic Your boiler has lost its unique digital identification code, meaning it no longer knows how to operate correctly and requires a professional to reprogram its settings. D.094 Diagnostic Your boiler is simply displaying a status message indicating that the historical error log has been successfully cleared. D.095 Diagnostic Your boiler is displaying a status message indicating the internal software version of a communication component, rather than reporting an actual fault. D.096 Diagnostic Your boiler has reverted to its original factory settings, which means any personalised heating or hot water schedules you previously saved have been cleared and will need to be set up again. D.098 Diagnostic Your boiler is struggling to recognize one of its internal electrical components, which is preventing it from starting up correctly. S.11 Status Your boiler is currently attempting to start up its fan to prepare for heating your hot water, which is a normal part of the ignition process. S.16 Status Your boiler's fan is still spinning after the hot water has been turned off, preventing the system from restarting safely. S.17 Status Your boiler is busy cooling itself down after providing hot water, but the water isn't moving through the system as quickly as it should. S13 Status Your boiler is struggling to light properly when you turn on your hot water taps.

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