Vaillant ecoTEC pro Installation And Maintenance Instructions Manual - page 36
Appendix
36
Installation and maintenance instructions ecoTEC pro 0020209589_01
Code
Meaning
Cause
F.25
Safety switch-off: Flue gas temperature too
high
Break in plug connection for optional flue gas safety temperature limiter
(STB), break in cable harness
F.26
Fault: Gas valve without function
Gas valve stepper motor not connected, multiple plug on the PCB not
plugged in correctly, interruption in cable harness, gas valve stepper
motor defective, electronics defective
F.27
Safety switch-off: Flame simulation
Moisture on the electronics, electronics (flame monitor) defective, gas
solenoid valve leaking
F.28
Failure during start-up: Ignition unsuccess-
ful
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
F.29
Failure during operation: Re-ignition unsuc-
cessful
Gas supply temporarily stopped, flue gas recirculation, condensate duct
blocked, defective earthing of product, ignition transformer has spark
failure
F.32
Fan fault
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
F.49
Fault: eBUS
Short circuit on eBUS, eBUS overload or two power supplies with differ-
ent polarities on the eBUS
F.61
Gas valve actuation fault
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
F.62
Gas valve switch-off delay
Delayed shutdown of gas valve detected
–
Secondary light (ignition and monitoring electrode indicates delayed
extinguishing of the flame signal)
–
Gas valve defective
–
PCB defective
F.63
Fault: EEPROM
Electronics defective
F.64
Fault: Electronics/NTC
Flow or return NTC short circuited, electronics defective
F.65
Fault: Electronics temp.
Electronics overheating due to external influences, electronics defective
F.67
Fault: Electronics/flame
Implausible flame signal, electronics defective
F.68
Fault: Unstable flame signal
Air in gas, gas flow pressure too low, incorrect air ratio, condensate
duct blocked, incorrect gas restrictor, ionisation flow interruption (cable,
electrode), flue gas recirculation, condensate duct
F.70
Invalid device specific number (DSN)
If spare parts fitted: Display and PCB replaced at same time and DSN
not reset, incorrect or missing output range coding resistance
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
circuit to GND in supply line to water pressure sensor or water pressure
sensor defective
F.74
Water pressure sensor signal outside cor-
rect range (too high)
Line to water pressure sensor has a short circuit to 5 V/24 V or internal
fault in the water pressure sensor
F.75
Fault: No pressure change detection when
starting pump
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
F.77
Fault: Flue non-return flap/condensate
pump
No response from flue non-return flap or condensate pump defective