BoilerFaultCodes Connection
No communication between the main PCB and the user interface | Electronics defective
Vaillant ecoFIT sustain 630 Fault codes & diagnostics
87 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
System Gas 2018-present
GC Number 41-694-32
Download the Vaillant ecoFIT sustain 630 manual
PDF
Versions & GC numbers
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 87 Unrated
Which version do you have?
The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 41-694-32 | ecoFIT sustain 630 VU 306/6-3 (H-GB) | 2018–present |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
Just want the most common Vaillant ecoFIT sustain 630 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 87 documented codes
Tap any card for details
F.00
Fault:Flowtemperaturesensor
F.01
Fault:Returntemperaturesensor
F.10
Shortcircuit:Flowtemperaturesensor
F.11
Shortcircuit:Returntemperaturesensor
F.12
Shortcircuit:Cylindertemperature sensor
F.13
Shortcircuit:Temperaturesensorforthe domestichotwatercylinder
F.20
Safetyshutdown:Overheatingtemperat- urereached
F.22
Insufficient water pressure
F.23
Safetyshutdown:Temperaturespread toogreat(NTC1/NTC2)
Showing 11–20 of 87
F.24
Safetyshutdown:Temperaturerisetoo fast
F.25
Safetyshutdown:Fluegastemperature toohigh
F.27
Safetyshutdown:Faultinflamedetec- tion
F.28
Fault:Ignitionunsuccessfulwhenstarting up
F.29
Fault:Flameloss
F.32
Fanfrostprotectionfunctionactive:Fan speedoutsidethetolerancevalues
F.49
eBUSfault:Voltagetoolow
F.61
Fault:Gasvalveassemblycontrol
F.62
Fault:Gasvalveswitch-offcontrol
F.63
Fault:EEPROM
Showing 21–30 of 87
F.64
Fault:Electronics/sensor/analogue-to- digitalconverter
F.65
Fault:Electronicstemperaturetoohigh
F.67
ValuesentbackbyASICisincorrect (flamesignal)
F.68
Fault:Unstableflame(analogueinput)
F.70
Invalidproductcode(DSN)
F.71
Fault:Flow/returntemperaturesensor
F.72
Fault:Deviationinthewaterpressure sensor/returntemperaturesensor
F.73
Fault:Waterpressuresensornotcon- nectedorhasshort-circuited
F.74
Fault:Electricalprobleminthewater pressuresensor
F.75
Fault:Pressuresensor
Showing 31–40 of 87
F.76
Thesafetycut-outintheprimaryheat exchangerisdefective
F.77
Fault:Condensateorsmoke
F.78
InterruptiontoDHWoutletsensorat externalcontrol
F.83
Fault:Dryfire
F.84
Fault:Flow/returntemperaturesensor
F.85
Fault:Temperaturesensor
F.86
Fault:Underfloorheatingcontact
F.87
Fault:Electrodes
F.88
Fault:Gasvalveassembly
F.89
Fault:Pump
Showing 41–50 of 87
F.91
Shortcircuit:Cylindertemperature sensor
F.97
Main PCB self-test failed | Main PCB defective
S.0
Heatingmode:Norequirement
S.01
Heatingmode:Fanprerun
S.02
Heatingmode:Pumpprerun
S.03
Heatingmode:Burnerignition
S.04
Product is working correctly (heating mode)
S.05
Heatingmode:Pump/fanoverrun
S.06
Heatingmode:Fanoverrun
S.07
Heatingmode:Pumpoverrun
Showing 51–60 of 87
S.08
Heatingmode:Temporaryshutdownafterheatingprocedure
S.10
Domestichotwatermode:Requirement
S.11
Domestichotwatermode:Fanprerun
S.13
Domestichotwatermode:Burnerignition
S.14
DHWmode:Burneron
S.15
DHWmode:Pump/fanoverrun
S.16
DHWmode:Fanoverrun
S.17
DHWmode:Pumpoverrun
S.20
Domestichotwatermode:Requirement
S.21
Domestichotwatermode:Fanprerun
Showing 61–70 of 87
S.22
Domestichotwatermode:Pumpprerun
S.23
Domestichotwatermode:Burnerignition
S.24
DHWmode:Burneron
S.25
DHWmode:Pump/fanoverrun
S.26
DHWmode:Fanoverrun
S.27
DHWmode:Pumpoverrun
S.28
Domestichotwatermode:Temporaryshutdownoftheburner
S.30
Roomthermostatisblockingheatingmode.
S.31
Noheatingdemand:Summermode,eBUScontrol,waitingperiod
S.32
Fanwaitingtime:Fanspeedoutsideofthetolerancevalues
Showing 71–80 of 87
S.33
Forcedfanoperationuntilthepressuremonitorisswitched
S.34
Frostprotectionactive
S.39
Underfloorheatingcontactopen
S.41
Waterpressuretoohigh
S.42
Fluenon-returnflapclosed
S.46
Frostprotectionmode(Comfort):Minimumload
S.53
Productinwaitingperiod/operatingblockfunctionduetowaterdeficiency(flow/returnspreadtoolarge)
S.54
Waitingperiod:Waterdeficiencyinthecircuit(flow/returnspreadtoolarge)
S.76
Maintenancemessage:Checkthewaterpressure
S.88
Productpurgingactive
Showing 81–87 of 87
S.91
Maintenance:Demomode
S.96
Automatictestprogramme:Returntemperaturesensor,heatingdemandsblocked.
S.97
Automatictestprogramme:Waterpressuresensor,heatingdemandsblocked.
S.98
Automatictestprogramme:Returntemperaturesensor,heatingdemandsblocked.
S.99
Internalautomatictestprogrammes
S.108
Purgingthecombustionchamber,faninoperation
S.109
Product'sstandbymodeactivated
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