Vaillant ecoTEC plus VUI, Installation And Maintenance Instructions Manual

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Troubleshooting
72
Installation and maintenance instructions ecoTEC plus 0020134833_01
13
Code Meaning Cause
F.49 eBUS fault Short circuit on eBUS, eBUS overload or two power supplies with different
polarities on the eBUS
F.52 Mass flow sensor connection fault Mass flow sensor not connected/disconnected, plug not connected or
incorrectly connected
F.53 Mass flow sensor fault Mass flow sensor faulty, filter below Venturi filter cap wet or blocked,
gas flow pressure too low
F.54 Gas pressure fault (in combination with F.28/F.29) No or too little gas supply pressure, gas valve closed
F.56 Fault: Mass flow sensor regulation Gas valve defective, cable harness to gas valve defective
F.57 Fault during comfort safety mode Ignition electrode highly corroded
F.61 Fault: Gas valve regulation - Short circuit/short to earth in cable harness for the gas valve
- Gas valve defective (coils shorted to earth)
- Electronics defective
F.62 Fault: Gas valve switch-off delay - Delayed shutdown of gas valve
- Delayed extinguishing of flame signal
- Gas valve leaking
- Electronics defective
F.63 EEPROM error Electronics defective
F.64 Electronics/NTC fault Flow or return NTC short circuited, electronics defective
F.65 Electronic temperature fault Electronics overheating due to external influences, electronics defective
F.67 Electronics/flame fault Implausible flame signal, electronics defective
F.68 Unstable flame signal fault Air in gas, gas flow pressure too low, wrong air ratio, condensate route
blocked, wrong gas restrictor, ionisation flow interruption (cables, elec-
trodes), flue gas recirculation, condensate route
F.70 Invalid device specific number (DSN) Spare part case: Display and PCB replaced at same time and DSN not set,
wrong or missing output range coding resistor
F.71 Flow NTC fault Flow temperature sensor signalling constant value:
- Flow temperature sensor incorrectly positioned at supply pipe.
- Flow temperature sensor defective.
F.72 Flow/return NTC fault Flow/return NTC temperature difference too great -> flow and/or return
temperature sensor defective
F.73 Water pressure sensor signal in the wrong range
(too low) Interruption/short circuit of water pressure sensor, interruption/short cir-
cuit to GND in supply line to water pressure sensor or water pressure sen-
sor defective
F.74 Water pressure sensor signal outside correct
range
(too high) Cable to water pressure sensor has short-circuited at 5 V/24 V
or internal fault in water pressure sensor
F.75 Fault, no pressure change detection when start-
ing pump Water pressure sensor and/or pump defective, air in heating installation,
too low water pressure in boiler; check adjustable bypass, connect external
expansion vessel to return
F.76 Overheating protection on primary heat
exchanger has responded Cable or cable connections for safety fuse in primary heat exchanger or
primary heat exchanger defective
F.77 Flue non-return flap/condensate pump fault No response from flue non-return flap or condensate pump defective
F.78 Interruption to DHW outlet sensor at external
controller UK link box is connected, but hot water NTC not bridged
F.80 Interruption or short circuit of inlet sofa second-
ary heat exchanger; only in connection with F.91 NTC defective, NTC cable defective, defective plug connection on NTC,
defective plug connection on actoSTOR electronics
Sensor plug has short to earth to the casing, short circuit in cable harness,
sensor faulty
F.81 actoSTOR load pump defective; only in combina-
tion with F.91 Cylinder is not fully charged after specified time.
- Check cylinder charging sensor and cylinder sensor
- Air in the actoSTOR pump
- Check the cable harness to the pump
- Check the impeller sensor and/or limiter in the boiler
- Diverter valve defective
- Secondary heat exchanger blocked
- Pump defective
13.2 Fault codes (continued)