D Overview Of Fault Codes - Vaillant ecoFIT sustain Series Installation And Maintenance Instructions Manual

Status code
S.98 Automatic test programme: Return temperature sensor, heating demands blocked.
S.99 Internal automatic test programmes
S.108 Purging the combustion chamber, fan in operation
S.109 Product's standby mode activated
D Overview of fault codes
Note
Since the code table is used for various products, some codes may not be visible for the product in question.
Fault code Meaning
F.00 Fault: Flow temperature sensor
F.01 Fault: Return temperature sensor
F.10 Short circuit: Flow temperature sensor
F.11 Short circuit: Return temperature sensor
F.12 and Short circuit: Cylinder temperature
F.91 sensor
F.13 Short circuit: Temperature sensor for the
domestic hot water cylinder
F.20 Safety shutdown: Overheating temperat-
ure reached
F.22 Safety shutdown: Water deficiency in the
boiler
F.23 Safety shutdown: Temperature spread
too great (NTC1/NTC2)
F.24 Safety shutdown: Temperature rise too
fast
F.25 Safety shutdown: Flue gas temperature
too high
F.27 Safety shutdown: Fault in flame detec-
tion
F.28 Fault: Ignition unsuccessful when starting
up
F.29 Fault: Flame loss
F.32 Fan frost protection function active: Fan
speed outside the tolerance values
F.49 eBUS fault: Voltage too low
F.61 Fault: Gas valve assembly control
F.62 Fault: Gas valve switch-off control
F.63 Fault: EEPROM
F.64 Fault: Electronics / sensor / analogue-to-
digital converter
F.65 Fault: Electronics temperature too high
0020230529_06 ecoFIT sustain Installation and maintenance instructions
Meaning
Possible cause
NTC plug not plugged in or has come loose, multiple plug on the PCB not
plugged in correctly, interruption in cable harness, NTC sensor defective
NTC plug not plugged in or has come loose, multiple plug on the PCB not
plugged in correctly, interruption in cable harness, NTC sensor defective
NTC sensor defective, short circuit in the cable harness, cable/housing
NTC sensor defective, short circuit in the cable harness, cable/housing
NTC sensor defective, short circuit in the cable harness, cable/housing
NTC sensor defective, short circuit in the cable harness, cable/housing
Incorrect earth connection between cable harness and product, flow or return
NTC defective (loose connection), stray spark via ignition cable, ignition plug
or ignition electrode
No or insufficient water in the product, water pressure sensor de-
fective, cable to the pump or to the water pressure sensor loose/not
connected/defective
Pump blocked, insufficient pump output, air in product, flow and return NTC
sensors connected the wrong way round
Pump blocked, insufficient pump output, air in product, system pressure too
low, non-return valve blocked/incorrectly installed
Break in plug connection for optional flue gas safety cut-out (SCO), break in
cable harness
Moisture on the electronics, electronics (flame monitor) defective, gas solen-
oid valve leaking
Gas meter defective or gas pressure switch has triggered, air in gas, gas
flow pressure too low, thermal cut-out has triggered, incorrect gas injector,
incorrect spare gas valve assembly, fault on the gas valve assembly, mul-
tiple plug on PCB incorrectly plugged in, break in cable harness, ignition sys-
tem (ignition transformer, ignition cable, ignition plug, ignition electrode) de-
fective, ionisation flow interrupted (cable, electrode), incorrect earthing of
product, electronics defective
Condensate siphon blocked
Gas supply temporarily stopped, flue gas recirculation, incorrect earthing of
product, ignition transformer has spark failure
Condensate siphon blocked
Plug on fan not correctly plugged in, multiple plug on PCB not correctly
plugged in, break in cable harness, fan blocked, Hall sensor defective, elec-
tronics defective
Short circuit on eBUS, eBUS overload or two power supplies with different
polarities on the eBUS
Short circuit/short-to-ground in cable harness to gas valve assembly, gas
valve assembly defective (coils shorted to earth), electronics defective
Delayed switch-off of gas valve assembly, delayed extinguishing of flame
signal, gas valve assembly leaking, electronics defective
Electronics defective
Flow or return NTC short circuited, electronics defective
Electronics overheating due to external influences, electronics defective
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