Vaillant ecoTEC plus VU GB 656/4-5 A Installation And Maintenance Instructions Manual page 36

Appendix
Code Meaning
F.27 Safety switch-off: Flame simulation
F.28 Failure during start-up: Ignition unsuccessful
F.29 Failure during operation: Re-ignition unsuccess-
ful
F.32 Fan fault
F.49 Fault: eBUS
F.61 Gas valve actuation fault
F.62 Gas valve switch-off delay
F.63 Fault: EEPROM
F.64 Fault: Electronics/NTC
F.65 Fault: Electronics temp.
F.67 Fault: Electronics/flame
F.70 Invalid device specific number (DSN)
F.71 Flow NTC fault
F.72 Flow/return NTC fault
F.73 Water pressure sensor signal in the wrong range
(too low)
F.74 Water pressure sensor signal outside correct
range (too high)
F.75 Fault: No pressure change detection when start-
ing pump
F.77 Fault: Flue non-return flap/condensate pump
con No communication with the PCB
36
Cause
Moisture on the electronics, electronics (flame monitor) defective, gas
solenoid valve leaking
Gas meter defective or gas pressure monitor has triggered, air in gas,
gas flow pressure too low, thermal isolator device (TAE) has triggered,
condensate duct blocked, incorrect gas restrictor, incorrect spare part
gas valve, fault on the gas valve, multiple plug on PCB incorrectly
plugged in, break in cable harness, ignition system (ignition transformer,
ignition cable, ignition plug, ignition electrode) defective, ionisation
current interrupted (cable, electrode), incorrect earthing of product,
electronics defective
Gas supply temporarily stopped, flue gas recirculation, condensate duct
blocked, defective earthing of product, ignition transformer has spark
failure
Plug on fan not correctly plugged in, multiple plug on PCB not correctly
plugged in, break in cable harness, fan blocked, Hall sensor defective,
electronics defective
Short circuit on eBUS, eBUS overload or two power supplies with differ-
ent polarities on the eBUS
The gas valve cannot be actuated
–
Cable harness supply line to the gas valve is defective (short to
earth, short circuit)
–
Gas valve defective
–
PCB defective
Delayed shutdown of gas valve detected
–
Secondary light (ignition and monitoring electrode indicates delayed
extinguishing of the flame signal)
–
Gas valve defective
–
PCB defective
Electronics defective
Flow or return NTC short circuited, electronics defective
Electronics overheating due to external influences, electronics defective
Implausible flame signal, electronics defective
If spare parts fitted: Display and PCB replaced at same time and DSN
not reset, incorrect or missing output range coding resistance
Flow temperature sensor signalling constant value:
–
Flow temperature sensor incorrectly positioned at supply pipe
–
Flow temperature sensor defective
Flow/return NTC temperature difference too great → flow and/or return
temperature sensor defective
Interruption/short circuit of water pressure sensor, interruption/short
circuit to GND in supply line to water pressure sensor or water pressure
sensor defective
Line to water pressure sensor has a short circuit to 5 V/24 V or internal
fault in the water pressure sensor
Water pressure sensor and/or pump defective, air in the heating installa-
tion, insufficient water in the product; check adjustable bypass, connect
external expansion vessel to the return
No response from flue non-return flap or condensate pump defective
Communication fault between display and PCB in the electronics box
Installation and maintenance instructions ecoTEC plus 0020214491_01