Vaillant Boiler Error Codes
If you’re experiencing an issue with your Vaillant Boiler, use our Vaillant Boiler Error Codes section to search by Boiler Make and Error Code to find out what the fault is.
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Vaillant Turbomax Plus 824/828E Boiler Error Codes
Error Code: F.00
Meaning: This means that your Flow NTC (Negative Temperature Coefficient Thermistor) cable is either defective or broken and needs to be replaced
Error Code: F.01
Possible Cause: NTC Faults
Meaning: The Flow NTC (Negative Temperature Coefficient Thermistor) cable is either defective or broken and needs to be replaced
Error Code: F.10
Error Code: F.11
Error Code: F.13
Error Code: F.20
Possible Cause: Boiler has exceeded the maximum temperature and needs to cool down
Error Code: F.22
Possible Cause: Dry fire / Low water in system / Overheat
Meaning: This means that there’s either no water in your system, you have a defective pump or the pump lead is defective
Error Code: F.24
Possible Cause: Low water / Pump Failure / Blockage
Meaning: Pump could be obstructed, running at low capacity, could be air trapped or the pressure might be too low.
Error Code: F.28
Possible Cause: Either insufficient gas in the system, a defective electrode, ignition lead or electronic ignitor
Error Code: F.29
Possible Cause: Flame extinguished
Meaning: Flame or pilot light has gone out – check flue duct or gas supply.
Error Code: F.60
Possible Cause: Gas valve control defective
Meaning: Cable loom (connects gas valve) might have short circuited, gas valve assembly defective or electronic control system issue.
Error Code: F.61
Possible Cause: Gas valve control defective
Meaning: Cable loom (connects gas valve) might have short circuited, gas valve assembly defective or electronic control system issue.
Error Code: F.62
Possible Cause: Defective gas valve closure mechanism
Meaning: Boiler has exceeded the maximum temperature and needs to cool down
Error Code: F.63
Possible Cause: EEPROM (Electrically Erasable Programmable Read-Only Memory) error
Meaning: Electronic fault.
Error Code: F.64
Possible Cause: Electronic system or sensor fault
Meaning: Flow or back flow NTC has short circuited, or an electronic fault
Error Code: F.65
Possible Cause: Electronic system temperature too high
Meaning: This can happen because of an external heat source or an electrical fault
Error Code: F.67
Possible Cause: Electronic fault in the flame system
Vaillant Ecomax PRO 18/28E Boiler Error Codes
Error Code: F.1
Possible Cause: Lack of gas, a fault with the ignition or flue – may need to adjust the gas valve or replace a defective electrode lead.
Error Code: F.4
Possible Cause: Ignition fault.
Error Code: F.5
Possible Cause: The system has suffered a fault due to overheating.
Error Code: F.6
Possible Cause: Your flow NTC has developed a fault.
Error Code: F.17
Possible Cause: Check the polarity of your system.
Error Code: F.24
Possible Cause: Pump-related faults – the pump could have failed, it may have over run or there could be an issue with the airlock
Vaillant Ecomax 828E Boiler Error Codes
Error Code: F.00
Possible Cause: All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
Error Code: F.04
Possible Cause: All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
Error Code: F.05
Possible Cause: All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
Error Code: F.10
Possible Cause: All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
Error Code: F.11
Possible Cause: A blockage in the appliance is preventing the system from flowing as it should.
Error Code: F.12
Possible Cause: A blockage in the appliance is affecting the system’s pressure.
Error Code: F.13
Possible Cause: The appliance is blocked because of a water deficiency.
Error Code: F.14
Possible Cause: All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
Error Code: F.15
Possible Cause: All of these are NTC faults, and are best resolved by first changing all NTC to make diagnosis earlier.
Error Code: F.20
Error Code: F.21
Possible Cause: The pilot flame has failed.
Error Code: F.22
Possible Cause: There is insufficient water in your system.
Vaillant EcoTEC 65kW Boiler Error Codes
Error Code: S.0
Possible Cause: Heating issue, no heat demand
Error Code: S.1
Possible Cause: Fan start-up error
Error Code: S.2
Possible Cause: Pump flow error
Error Code: S.3
Possible Cause: Heating mode error – ignition problem
Error Code: S.4
Possible Cause: Heat mode – burner on error
Error Code: S.6
Possible Cause: Heating mode – fan overrun error
Error Code: S.7
Possible Cause: Heating mode – pump overrun error
Error Code: S.8
Possible Cause: Heating remaining cut off for XX amount of time
Error Code: S.20
Possible Cause: Hot water requirement error
Error Code: S.22
Possible Cause: Hot water handling pump flow error
Error Code: S.24
Possible Cause: Hot water operation burner is on
Error Code: S.31
Possible Cause: No heat demand summer operating mode
Error Code: S.34
Possible Cause: Heating mode frost protection error
Error Code: S.85
Possible Cause: Service message quantity of circulation water
Vaillant EcoTEC Pro / EcoTEC Plus Boiler Error Codes
Error Code: F.00
Possible Cause: Flow temperature sensor interruption
Error Code: F.0
Possible Cause: Flow temperature sensor interruption
Error Code: F.10
Possible Cause: Flow NTC short circuit
Error Code: F.11
Possible Cause: Return NTC short circuit
Error Code: F.20
Possible Cause: Safety switch off temperature limiter
Error Code: F.22
Possible Cause: Safety switch off low water pressure
Error Code: F.23
Possible Cause: Safety switch off temperature difference too great
Error Code: F.24
Possible Cause: Safety switch off temperature is rising to fast
Error Code: F.25
Possible Cause: Safety switch off flue gas temperature too high
Error Code: F.26
Possible Cause: Error with gas valve – possible no function
Error Code: F.27
Possible Cause: Safety switch off flame simulation
Error Code: F.28
Possible Cause: Failure during start up – ignition unsuccessful to start
Error Code: F.29
Possible Cause: Failure during operation – re-ignition unsuccessful
Error Code: F.32
Possible Cause: Fan error
Error Code: F.49
Possible Cause: eBUS error – possible short circuit
Error Code: F.61
Possible Cause: Error with gas valve regulation
Error Code: F.62
Possible Cause: Error with gas valve – switch off delay
Error Code: F.63
Possible Cause: EEPROM error
Error Code: F.64
Possible Cause: Electronics / NTC error
Error Code: F.65
Possible Cause: Electronic temperature error could be overheating due to external influences
Error Code: F.68
Possible Cause: Unstable flame signal error air in gas
Error Code: F.70
Possible Cause: Invalid device specific number (DSN)
Error Code: F.71
Possible Cause: Flow NTC error – flow temperature sensor signal constant value
Error Code: F.72
Possible Cause: Flow return NTC error – temperature difference too great
Error Code: F.73
Possible Cause: Water pressure sensor signal in the wrong range, it is too low
Error Code: F.74
Possible Cause: Water pressure sensor signal outside correct range, the sensor signal is too high
Error Code: F.75
Possible Cause: Error with pressure – no pressure change detection when starting the pump
Error Code: F.76
Possible Cause: Overheating protection on – primary heat exchanger has responded
Error Code: F.77
Possible Cause: Flue non return flap condensate pump error
Error Code: F.78
Possible Cause: Interruption to DHW outlet sensor at external controller
Error Code: F.83
Possible Cause: Flow and or return temperature sensor error
Error Code: F.84
Possible Cause: Error with flow/return temperature sensor temperature changing error
Error Code: F.85
Possible Cause: Error with flow and return temperature, sensor incorrectly fitted
Error Code: CONNECTION
Possible Cause: No communication with the PCB
Vaillant EcoTEC Pro / EcoTEC Plus Boiler Error Codes
Error Code: S.00
Possible Cause: Heating mode error – no heat demand
Error Code: S.01
Possible Cause: Heating mode fan start-up
Error Code: S.02
Possible Cause: Heating mode error – water pump running
Error Code: S.03
Possible Cause: Heating mode – ignition sequence error
Error Code: S.04
Possible Cause: Heating mode – burner ignited
Error Code: S.06
Possible Cause: Heating mode – fan overrun error
Error Code: S.07
Possible Cause: Heating mode – pump overrun error
Error Code: S.08
Possible Cause: Heating remaining cut off time xx minutes
Error Code: S.10
Possible Cause: Hot water demand via impeller sensor
Error Code: S.11
Possible Cause: DHW mode fan start up error
Error Code: S.13
Possible Cause: DHW mode ignition error
Error Code: S.14
Possible Cause: Hot water demand via fan sensor error
Error Code: S.15
Possible Cause: DHW mode pump and fan overrun
Error Code: S.16
Possible Cause: DHW mode – fan overrun error
Error Code: S.17
Possible Cause: DHW mode – pump overrun error
Error Code: S.20
Possible Cause: DHW mode – burner on error
Error Code: S.21
Possible Cause: DHW mode – fan start up error
Error Code: S.22
Possible Cause: DHW demand – error pump running
Error Code: S.23
Possible Cause: DHW ignition error
Error Code: S.24
Possible Cause: DHW mode – burner error
Error Code: S.25
Possible Cause: DHW mode – pump or fan overrun error
Error Code: S.26
Possible Cause: DHW mode – fan overrun
Error Code: S.27
Possible Cause: DHW mode – pump overrun
Error Code: S.28
Possible Cause: Hot water burner anti-cycling time
Error Code: S.30
Possible Cause: Room thermostat is blocking heating mode
Error Code: S.31
Possible Cause: No heat demand boiler in summer operating mode
Error Code: S.32
Possible Cause: Waiting period because of fan speed deviation
Error Code: S.34
Possible Cause: Heating mode frost protection error
Error Code: S.39
Possible Cause: Burner off contact has been triggered this could be because of contact thermostat or condensate pump
Error Code: S.40
Possible Cause: Comfort safety mode active
Error Code: S.41
Possible Cause: Water pressure > 2.8 bar
Error Code: S.42
Possible Cause: Flue non return flap return signal blocks burner operation
Error Code: S.46
Possible Cause: Comfort safety mode flame loss at minimum load
Error Code: S.53
Possible Cause: Boiler is in waiting period of modulation f block function due to water shortage
Error Code: S.54
Possible Cause: Boiler is in waiting period of operation, blocking function as a result
Error Code: S.57
Possible Cause: Waiting period comfort safety mode
Error Code: S.58
Possible Cause: Modulation limitation due to noise / wind error
Error Code: S.61
Possible Cause: Gas family check unsuccessful
Vaillant EcoTEC Plus Regular Gas Boiler Error Codes
Error Code: S.20
Possible Cause: Warnstar demand
Error Code: S.21
Possible Cause: Fan running
Error Code: S.22
Possible Cause: Pump running
Error Code: S.23
Possible Cause: Ignition sequence
Error Code: S.24
Possible Cause: Burner ignited
Error Code: S.25
Possible Cause: Fan and water pump running
Error Code: S.26
Possible Cause: Fan overrun
Error Code: S.27
Possible Cause: Pump overrun
Error Code: S.28
Possible Cause: Anti-cycling mode
Error Code: S.30
Possible Cause: No heating demand from external controls
Error Code: S.31
Possible Cause: Central heating thermostat knob turned off
Error Code: S.32
Possible Cause: Heat exchanger antifreeze active as fan speed variation is too high
Error Code: S.34
Possible Cause: Anti-frost mode is active
Error Code: S.36
Possible Cause: Not heating demand form low voltage
Error Code: S.41
Possible Cause: Water pressure greater than 2.9 bar
Error Code: S.42
Possible Cause: Response from accessory module or defective condensate pump is blocking burner operation
Error Code: S.53
Possible Cause: Appliance is within the waiting period of the block operation function due to water shortage
Error Code: S.54
Possible Cause: Appliance is within the waiting period of the block operation due to water shortage
Error Code: S.96
Possible Cause: Return sensor error
Error Code: S.98
Possible Cause: Flow return sensor check is running demand is block
Error Code: D.0
Possible Cause: Heating part load error
Error Code: D.1
Possible Cause: Water pump overrun – time for heat mode
Error Code: D.2
Possible Cause: Max burner anti-cycling period at 20c flow temperature
Error Code: D.3
Possible Cause: Hot water flow temperature reading
Error Code: D.4
Possible Cause: Current temperature for warm stat sensor
Error Code: D.7
Possible Cause: Warm start temperature target value
Error Code: D.8
Possible Cause: External controls heat demand
Error Code: D.9
Possible Cause: Flow target temperature from external analogue regulator terminal
Error Code: D10
Possible Cause: Status internal heating pump error
Error Code: D1.11
Possible Cause: Status external heating pump error
Error Code: D.12
Possible Cause: Cylinder charging pump via accessory module
Error Code: D.13
Possible Cause: Hot water circulation pump
Error Code: D.17
Possible Cause: Heating glow return regulation
Error Code: D.18
Possible Cause: Pump mode return
Error Code: D.19
Possible Cause: Operating modes of the two speed heating pump
Error Code: D.20
Possible Cause: Maximum set value for target cylinder
Error Code: D.22
Possible Cause: Hot water demand
Error Code: D.23
Possible Cause: Summer/Winter function
Error Code: D.25
Possible Cause: Hot water activation via ebus control
Error Code: D.27
Possible Cause: Switching accessory relay 1
Error Code: D.28
Possible Cause: Switching accessory relay 2
Error Code: D.30
Possible Cause: Control signal for both gas valves
Error Code: D.33
Possible Cause: Fan speed target value
Error Code: D.34
Possible Cause: Fan speed actual value
Error Code: D.36
Possible Cause: Hot water flow sensor
Error Code: D.40
Possible Cause: Flow temperature target value
Error Code: D.41
Possible Cause: Return temperature actual value
Error Code: D.44
Possible Cause: Digitised ionisation potential error
Error Code: D.47
Possible Cause: Outside temperature with weather compensator – Vaillant controller only
Error Code: D.50
Possible Cause: Offset for minimum speed
Error Code: D.51
Possible Cause: Offset for maximum speed
Error Code: D.58
Possible Cause: Activation of solar reheating
Error Code: D.60
Possible Cause: Number of safety temperature cut off
Error Code: D.61
Possible Cause: Number of unsuccessful lockouts
Error Code: D.64
Possible Cause: Average ignition times
Error Code: D.65
Possible Cause: Maximum ignition time
Error Code: D.68
Possible Cause: Unsuccessful ignitions in the first attempt
Error Code: D.69
Possible Cause: Unsuccessful ignition for the second time
Error Code: D.70
Possible Cause: Set diverter valve position
Error Code: D.71
Possible Cause: Maximum setting of heater control knob
Error Code: D.72
Possible Cause: Pump overrun time after warm start
Error Code: D.73
Possible Cause: Off set for warm start target value
Error Code: D.75
Possible Cause: Maximum charging time for a storage without own controller
Error Code: D.76
Possible Cause: Remaining burner anti-cycling time in min
Error Code: D.77
Possible Cause: Limitation of cylinder charging in output in kW
Error Code: D.78
Possible Cause: Limitation of cylinder charging temperature in c
Error Code: D.80
Possible Cause: Operating hours heating
Error Code: D.81
Possible Cause: Operating hours hot water generation
Error Code: D.82
Possible Cause: Burner start up in heating mode
Error Code: D.83
Possible Cause: Burner start up in hot water mode
Error Code: D.84
Possible Cause: Maintenance indicator – number of hours until the next maintenance
Error Code: D.90
Possible Cause: Digital regulator status
Error Code: D.91
Possible Cause: DCF status with connected external probe
Error Code: D.93
Possible Cause: DSN appliance variant setting
Error Code: D.96
Possible Cause: Factory setting
Error Code: D.97
Possible Cause: Activation of the second diagnostic level
Vaillant EcoTEC Plus Gas Boiler Error Codes
Error Code: P.00
Possible Cause: The heating circuit and hot water circuit are purged
Error Code: P.01
Possible Cause: Maximum load test program error
Error Code: P.02
Possible Cause: Minimum load test program
Error Code: P.06
Possible Cause: Filling mode test program
Vaillant EcoTEC Gas Boiler Error Codes
Error Code: D.0
Possible Cause: Heating part load error
Error Code: D.1
Possible Cause: Water pump overrun – time for heat mode
Error Code: D.2
Possible Cause: Max burner anti-cycling period at 20c flow temperature
Error Code: D.3
Possible Cause: Hot water flow temperature reading
Error Code: D.4
Possible Cause: Current temperature for warm stat sensor
Error Code: D.5
Possible Cause: Set value of flow temperature or target value of return
Error Code: D.7
Possible Cause: Warm start temperature target value
Error Code: D.8
Possible Cause: External controls heat demand
Error Code: D.9
Possible Cause: Flow target temperature from external analogue regulator terminal
Error Code: D.10
Possible Cause: Status internal heating pump error
Error Code: D.11
Possible Cause: Status external heating pump error
Error Code: D.12
Possible Cause: Cylinder charging pump via accessory module
Error Code: D.13
Possible Cause: Hot water circulation pump
Error Code: D.14
Possible Cause: Pump speed target value
Error Code: D.15
Possible Cause: Pump speed actual value
Error Code: D.17
Possible Cause: Heating flow return regulation
Error Code: D.18
Possible Cause: Pump operating mode
Error Code: D.20
Possible Cause: Maximum set value for target cylinder
Error Code: D.22
Possible Cause: Hot water demand
Error Code: D.23
Possible Cause: Summer/Winter function
Error Code: D.24
Possible Cause: Not relevant
Error Code: D.25
Possible Cause: Hot water activation via eBus control
Error Code: D.26
Possible Cause: Additional relay control ecoTec
Error Code: D.27
Possible Cause: Switching accessory relay 1
Error Code: D.28
Possible Cause: Switching accessory relay 2
Error Code: D.30
Possible Cause: Control signal for both gas valves
Error Code: D.33
Possible Cause: Fan speed target value
Error Code: D.34
Possible Cause: Fan speed actual value
Error Code: D.35
Possible Cause: Not relevant
Error Code: D.40
Possible Cause: Flow temperature target value
Error Code: D.41
Possible Cause: Return temperature actual value
Error Code: D.44
Possible Cause: Digitised ionisation – potential error
Error Code: D.47
Possible Cause: Outside temperature with weather compensator – Vaillant controller only
Error Code: D.50
Possible Cause: Offset for minimum speed
Error Code: D.51
Possible Cause: Offset for maximum speed
Error Code: D.60
Possible Cause: Number of safety temperature cut offs
Error Code: D.61
Possible Cause: Number of unsuccessful lockouts
Error Code: D.64
Possible Cause: Average ignition times
Error Code: D.65
Possible Cause: Maximum ignition time
Error Code: D.67
Possible Cause: Remaining burner anti-cycling time
Error Code: D.68
Possible Cause: Unsuccessful ignitions in the first attempt
Error Code: D.69
Possible Cause: Unsuccessful ignition for the second time
Error Code: D.70
Possible Cause: Set diverter valve position
Error Code: D.71
Possible Cause: Maximum setting of heater control knob
Error Code: D.72
Possible Cause: Pump overrun time after warm start
Error Code: D.75
Possible Cause: Maximum charging time for a storage without own controller
Error Code: D.76
Possible Cause: Remaining burner anti-cycling time in min
Error Code: D.77
Possible Cause: Limitation of cylinder charging in output in kW
Error Code: D.78
Possible Cause: Limitation of cylinder charging temperature in celsius
Error Code: D.80
Possible Cause: Operating hours heating
Error Code: D.81
Possible Cause: Operating hours hot water generation
Error Code: D.82
Possible Cause: Burner start up in heating mode
Error Code: D.83
Possible Cause: Burner start up in hot water mode
Error Code: D.84
Possible Cause: Maintenance indicator – number of hours until the next maintenance
Error Code: D.90
Possible Cause: Digital regulator status
Error Code: D.91
Possible Cause: DCF status with connected external probe
Error Code: D.93
Possible Cause: DSN appliance variant setting
Error Code: D.94
Possible Cause: Factory setting
Error Code: D.97
Possible Cause: Activation of the second diagnostic level
Error Code: D.98
Possible Cause: Telephone a heating engineer