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2021 Vaillant Boiler Error & Fault Codes


Vaillant boilers employ a number of error codes of which the most common relate to the vent system and its integrated pressure relief valve. In this article we'll take a look at what the codes mean and what you can do to correct any problems associated with them.

Fault codes are codes related to problems in your home's central heating system. They're a tool for diagnosing problems, since they give you a numbered list of the different things that might be wrong with your boiler.

Vaillant boiler error codes will enable you to discover the cause behind the faulty circuitry sooner rather than later. You can then get the boiler repaired quickly, so it's back up and running to heat your home once again. If you are a DIY enthusiast, why not try to diagnose the problem yourself? With a little know-how, you should be able to identify the error code by working through a series of checks.

Vaillant EcoTEC 65kW Boiler Error Codes


The Vaillant EcoTEC is a high-quality condensing boiler, which is a great choice for homeowners in areas of the country that experience significant heating seasons. The EcoTEC's energy efficiency capabilities are top-notch, and even better that the technology behind them is user-friendly.

Below is a guide to Vaillant EcoTEC 65kW boiler error codes, and what they mean. These are the error codes displayed on the EcoTEC's electronic control panel. They identify minor and major faults in the system system, or provide information on its status.

Fault Code Possible Cause
S.OHeating issue, no heat demand
S.1Fan start-up error
S.2Pump flow error
S.3Heating mode error – ignition problem
S.4Heat mode – burner on error
S.6Heating mode – fan overrun error
S.7Heating mode – pump overrun error
S.8Heating remaining cut off for X amount of time
S.31No heat demand summer operating mode
S.34Heating mode frost protection error
S.20Hot water requirement error
S.22Hot water handling pump flow error
S.24Hot water operation burner is on
S.85Service message quantity of circulation water

Vaillant EcoTEC Pro / EcoTEC Plus Boiler Error Codes


There are many things to check when diagnosing boiler problems. These error codes are only one small part of it. However, it's important to have an understanding of them because they give a good indication of what the fault is and where to start looking for it.

There are a number of problems you can experience with a Vaillant EcoTec Pro or EcoTec Plus boiler. These boilers are more modern and advanced than other heaters, so the error codes tend to be different than other models. Here's a chart of the error code formats for these particular models.

Fault Code Possible Cause
F.00 / F.0Flow temperature sensor interruption
F.01 / F.1Return temperature sensor interruption
F.10Flow NTC short circuit
F.11Return NTC short circuit
F.20Safety switch off temperature limiter
F.22Safety switch off low water pressure
F.23Safety switch off temperature difference too great
F.24Safety switch off temperature is rising to fast
F.25Safety switch off flue gas temperature too high
F.26Error with gas valve – possible no function
F.27Safety switch off flame simulation
F.28Failure during start up – ignition unsuccessful to start
F.29Failure during operation – re-ignition unsuccessful
F.32Fan error
F.49eBUS error – possible short circuit
F.61Error with gas valve regulation
F.62Error with gas valve – switch off delay
F.63EEPROM error
F.64Electronics / NTC error
F.65Electronic temperature error could be overheating due to external influences
F.67Electronics flame signal error
F.68Unstable flame signal error air in gas
F.70Invalid device specific number (DSN)
F.71Flow NTC error – flow temperature sensor signal constant value
F.72Flow return NTC error – temperature difference too great
F.73Water pressure sensor signal in the wrong range, it is too low
F.74Water pressure sensor signal outside correct range, the sensor signal is too high
F.75Error with pressure – no pressure change detection when starting the pump
F.76Overheating protection on – primary heat exchanger has responded
F.77Flue non return flap condensate pump error
F.78Interruption to DHW outlet sensor at external controller
F.83Flow and or return temperature sensor error
F.84Error with flow/return temperature sensor temperature changing error
F.85Error with flow and return temperature, sensor incorrectly fitted
CONNECTIONNo communication with the PCB
S.00Heating mode error – no heat demand
S.01Heating mode fan start-up
S.02Heating mode error – water pump running
S.03Heating mode – ignition sequence error
S.04Heating mode – burner ignited
S.06Heating mode – fan overrun error
S.07Heating mode – pump overrun error
S.08Heating remaining cut off time X minutes
S.10Hot water demand via impeller sensor
S.11DHW mode fan start up error
S13DHW mode ignition error
S.14Hot water demand via fan sensor error
S.15DHW mode pump and fan overrun
S.16DHW mode – fan overrun error
S.17DHW mode – pump overrun error
S.20DHW mode – burner on error
S.21DHW mode – fan start up error
S.22DHW demand – error pump running
S.23DHW ignition error
S.24DHW mode – burner error
S.25DHW mode – pump or fan overrun error
S.26DHW mode – fan overrun
S.27DHW mode – pump overrun
S.28Hot water burner anti-cycling time
S.30Room thermostat is blocking heating mode
S.31No heat demand boiler in summer operating mode
S.32Waiting period because of fan speed deviation
S.34Heating mode frost protection error
S.39Burner off contact has been triggered this could be because of contact thermostat or condensate pump
S.40Comfort safety mode active
S.41Water pressure > 2.8 bar
S.42Flue non return flap return signal blocks burner operation
S.46Comfort safety mode flame loss at minimum load
S.53Boiler is in waiting period of modulation f block function due to water shortage
S.54Boiler is in waiting period of operation, blocking function as a result
S.57Waiting period comfort safety mode
S.58Modulation limitation due to noise / wind error
S.61Gas family check unsuccessful

Vaillant EcoTEC Plus Regular Gas Boiler Error Codes


EcoTEC Plus Regular gas boilers are a very popular range of heating systems. They have many good features, including:  low emissions, high efficiency, small size, and long life. Like the vast majority of boilers they have a self control system which checks the boiler and all the major components regularly and indicates any faults on a control board. Also like all other boilers - and most electrical appliances - EcoTEC Plus error codes can occur for a number of reasons.

The following is a list of common boiler error codes that you may see on your EcoTEC Plus Regular boiler. It's important to remember that some of these codes can be caused by more than one problem, so try to troubleshoot based on the symptom, not just the code.

Fault Code Possible Cause
S.20Warnstar demand
S.21Fan running
S.22Pump running
S.23Ignition sequence
S.24Burner ignited
S.25Fan and water pump running
S.26Fan overrun
S.27Pump overrun
S.28Anti-cycling mode
S.30No heating demand from external controls
S.31Central heating thermostat knob turned off
S.32Heat exchanger antifreeze active as fan speed variation is too high
S.34Anti-frost mode is active
S.36Not heating demand form low voltage
S.41Water pressure greater than 2.9 bar
S.42Response from accessory module or defective condensate pump is blocking burner operation
S.53Appliance is within the waiting period of the block operation function due to water shortage
S.54Appliance is within the waiting period of the block operation due to water shortage
S.96Return sensor error
S.98Flow return sensor check is running demand is block
D.0Heating part load error
D.1Water pump overrun – time for heat mode
D.2Max burner anti-cycling period at 20c flow temperature
D.3Hot water flow temperature reading
D.4Current temperature for warm stat sensor
D.7Warm start temperature target value
D.8External controls heat demand
D.9Flow target temperature from external analogue regulator terminal
D.10Status internal heating pump error
D,11Status external heating pump error
D.12Cylinder charging pump via accessory module
D.13Hot water circulation pump
D.22Hot water demand
D.23Summer/Winter function
D.25Hot water activation via ebus control
D.30Control signal for both gas valves
D.33Fan speed target value
D.34Fan speed actual value
D.36Hot water flow sensor
D.40Flow temperature target value
D.41Return temperature actual value
D.44Digitised ionisation potential error
D.47Outside temperature with weather compensator – Vaillant controller only
D.76Remaining burner anti-cycling time in min
D.90Digital regulator status
D.91DCF status with connected external probe
D.97Activation of the second diagnostic level
D.17Heating glow return regulation
D.18Pump mode return
D.19Operating modes of the two speed heating pump
D.20Maximum set value for target cylinder
D.27Switching accessory relay 1
D.28Switching accessory relay 2
.50Offset for minimum speed
D.51Offset for maximum speed
D.58Activation of solar reheating
D.60Number of safety temperature cut off
D.61Number of unsuccessful lockouts
D.64Average ignition times
D.65Maximum ignition time
D.68Unsuccessful ignitions in the first attempt
D.69Unsuccessful ignition for the second time
D.70Set diverter valve position
D.71Maximum setting of heater control knob
D.72Pump overrun time after warm start
D.73Off set for warm start target value
D.75Maximum charging time for a storage without own controller
D.77Limitation of cylinder charging in output in kW
D.78Limitation of cylinder charging temperature in c
D.80Operating hours heating
D.81Operating hours hot water generation
D.82Burner start up in heating mode
D.83Burner start up in hot water mode
D.84Maintenance indicator – number of hours until the next maintenance
D.93DSN appliance variant setting
D.96Factory setting

Vaillant EcoTEC Plus Gas Boiler Error Codes


The Vaillant EcoTEC Plus is an intelligent boiler. It provides more benefits than a standard boiler, like advanced diagnostics, and highly efficient combustion. However, as with all advanced technologies, there are some problems that can develop.

The EcoTEC Plus Gas boiler error codes will help you diagnose the problem by letting you know what's going on inside your boiler. That way, when you're troubleshooting, you'll have a better idea of what might be causing your system to give error signals.

Below is a full list of the most commonly-encountered EcoTEC Plus Gas boiler error codes, their meanings, and action required.

Fault Code Possible Cause
P.00The heating circuit and hot water circuit are purged
P.01Maximum load test program error
P.02Minimum load test program
P.06Filling mode test program

Vaillant EcoTEC Gas Boiler Error Codes


The Vaillant EcoTEC Boilers are considered by many to be the best make of gas boiler on the market. But, just like any other piece of technology, they can and will occasionally fail. The problem with gas boilers is that little or nothing is relayed to the homeowner as to what the fault actually is. Meaning that a plethora of different error codes might be displayed in a short period of time, causing great confusion.

If you have an EcoTEC gas boiler, you should know how to read its error codes. Your heating system's error codes will tell you about malfunctions in the different parts of your boiler, allowing you to fix them and improve its efficiency.

Here's a list of the most common boiler error codes you might see on an EcoTEC Gas Boiler. These examples are based in the UK, but logic is fairly consistent across other countries, and this should hopefully be helpful regardless of where you're located.

Fault Code Possible Cause
D.0Heating part load error
D.1Water pump overrun – time for heat mode
D.2Max burner anti-cycling period at 20c flow temperature
D.3Hot water flow temperature reading
D.4Current temperature for warm stat sensor
D.5Set value of flow temperature or target value of return
D.7Warm start temperature target value
D.8External controls heat demand
D.9Flow target temperature from external analogue regulator terminal
D.10Status internal heating pump error
D.11Status external heating pump error
D.12Cylinder charging pump via accessory module
D.13Hot water circulation pump
D.15Pump speed actual value
D.22Hot water demand
D.23Summer/Winter function
D.24Not relevant
D.25Hot water activation via eBus control
D.30Control signal for both gas valves
D.33Fan speed target value
D.34Fan speed actual value
D.35Not relevant
D.40Flow temperature target value
D.41Return temperature actual value
D.44Digitised ionisation – potential error
D.47Outside temperature with weather compensator – Vaillant controller only
D.76Remaining burner anti-cycling time in min
D.90Digital regulator status
D.91DCF status with connected external probe
D.97Activation of the second diagnostic level
D.98Telephone a heating engineer
D.14Pump speed target value
D.17Heating flow return regulation
D.18Pump operating mode
D.20Maximum set value for target cylinder
D.26Additional relay control ecoTec
D.27Switching accessory relay 1
D.28Switching accessory relay 2
D.50Offset for minimum speed
D.51Offset for maximum speed
D.60Number of safety temperature cut offs
D.61Number of unsuccessful lockouts
D.64Average ignition times
D.65Maximum ignition time
D.67Remaining burner anti-cycling time
D.68Unsuccessful ignitions in the first attempt
D.69Unsuccessful ignition for the second time
D.70Set diverter valve position
D.71Maximum setting of heater control knob
D.72Pump overrun time after warm start
D.75Maximum charging time for a storage without own controller
D.77Limitation of cylinder charging in output in kW
D.78Limitation of cylinder charging temperature in celsius
D.80Operating hours heating
D.81Operating hours hot water generation
D.82Burner start up in heating mode
D.83Burner start up in hot water mode
D.84Maintenance indicator – number of hours until the next maintenance
D.93DSN appliance variant setting
D.96Factory setting

Vaillant EcoMax Pro 18/28E Boiler Error Codes


There are numerous reasons why your Vaillant EcoMax Pro 18/28E boiler could display a boiler error code. These include problems with the power supply, the heating controls, or a fault with your home's water pressure.

Here's a handy table to help you understand the possible error codes. If you do find yourself with an error code on your 18/28E boiler, at least now you'll have some idea of what it means, and be able to take corrective action.

Fault Code Possible Cause
F.1Lack of gas, a fault with the ignition or flue – may need to adjust the gas valve or replace a defective electrode lead.
F.4Ignition fault.
F.5The system has suffered a fault due to overheating.
F.6Your flow NTC has developed a fault.
F.17Check the polarity of your system.
F.24Pump-related faults – the pump could have failed, it may have over run or there could be an issue with the airlock

Vaillant Ecomax Pro 828E Boiler Error Codes


Here are the most common fault error codes you're likely to see, along with explanations for what they mean. Combining this information with the user-friendly ecomax pro 828e boiler manual will give you the knowledge you need to arrange repairs to your home's heating system.

Vaillant Ecomax Pro 828E error codes can be classified in two main types: the boiler display and the control board. Both of them are discussed here.

Fault Code Possible Cause
F.00NTC Faults
F.04NTC Faults
F.05NTC Faults
F.10NTC Faults
F.14NTC Faults
F.15NTC Faults
F.21The pilot flame has failed.
F.22There is insufficient water in your system.
F.11A blockage in the appliance is preventing the system from flowing as it should.
F.12A blockage in the appliance is affecting the system’s pressure.
F.13The appliance is blocked because of a water deficiency.

Vaillant Turbomax Plus 824/828E Boiler Error Codes


The Vaillant Turbomax Plus 824/828E Boiler Error Codes are displayed in the form of digital messages. If an error is recognized, flashing panels will appear at the top left corner on the front of your boiler. A sound buzzer may also sound to alert you that an error has been detected. This table helps you understand what these codes mean and what actions to take when it is displayed on your machine's operating panel.

Fault Code Possible Cause
F.00NTC Faults
F.01NTC Faults
F.10NTC Faults
F.11NTC Faults
F.13NTC Faults
F.20Boiler has exceeded the maximum temperature and needs to cool down
F.22Dry fire / Low water in system / Overheat
F.24Low water / Pump Failure / Blockage
F.28Either insufficient gas in the system, a defective electrode, ignition lead or electronic ignitor
F.29Flame extinguished
F.60Gas valve control defective
F.61Gas valve control defective
F.62Defective gas valve closure mechanism
F.63EEPROM (Electrically Erasable Programmable Read-Only Memory) error
F.64Electronic system or sensor fault
F.65Electronic system temperature too high
F.67Electronic fault in the flame system
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