Vaillant ECOTEC PLUS VU 80 Installation And Maintenance Instructions Manual page 60

14 Troubleshooting
14.2.9 Overview of fault codes
Code Meaning
F.00 Flow temperature sensor interruption
F.01 Return temperature sensor interruption
F.10 Short circuit, flow sensor
F.11 Short circuit, return sensor
F.20 Temperature safety switch-off
F.22 Low water pressure safety switch-off
F.23 Safety switch-off: Temperature difference too great
F.24 Safety switch-off: Temperature rise too fast
F.25 Safety switch-off: Flue gas temperature too high
F.27 Safety switch-off: Flame simulation
F.28 Failure during start-up: Ignition unsuccessful
F.29 Failure during operation: Re-ignition unsuccessful
F.32 Fan fault
F.34 Safety switch-off: pressure monitoring
F.35 Flue pipe fault
F.49 eBUS fault
F.61 Fault: Gas valve regulation
F.62 Fault: Gas valve switch-off delay
F.63 EEPROM fault
F.64 Electronics/sensor fault
F.65 Electronic temperature fault
F.67 Electronics/flame fault
F.70 Invalid device code
14.3 Fault codes
60
Cause
NTC plug not plugged in or has come loose, multiple plug on the PCB
not plugged in correctly, interruption in cable harness, NTC defective
NTC plug not plugged in or has come loose, multiple plug on the PCB
not plugged in correctly, interruption in cable harness, NTC defective
Sensor plug has a short to the casing, short-circuit in cable harness,
sensor faulty
Sensor plug has a short to the casing, short-circuit in cable harness,
sensor faulty
Earth connection of cable harness to boiler not correct, when the
burner cover safety cut-out triggers: burner door seal or burner iso-
lation defective.
When the flow safety cut-out triggers: pump fault
No or too little water in the boiler, water pressure sensor defective,
cable to pump or water pressure sensor loose/not connected/
defective
Pump blocked, insufficient pump output, air in boiler, flow and return
NTC interchanged
Pump blocked, poor pump performance, air in boiler, system pressure
too low, non-return valve blocked/incorrectly installed
Break in plug connection for optional flue gas safety temperature
limiter (safety cut-out), break in cable harness
Moisture on the electronics, electronics (flame monitor) defective,
gas solenoid valve leaking
Gas meter defective or gas pressure monitor has been triggered, air
in gas, gas connection pressure (gas flow pressure) too low,
Thermal isolator device (TAE) has been triggered, condensate duct
blocked, incorrect gas restrictor, incorrect ET gas valve, failure at gas
valve, multiple plug on PCB incorrectly plugged in, break in cable har-
ness, ignition system (ignition transformer, ignition cable, ignition
plug, ignition electrode) defective, ionisation current interrupted
(cable, electrode), incorrect earthing of boiler, electronics defective
Gas supply temporarily stopped, flue gas recirculation, condensate
duct blocked, faulty earthing of boiler, ignition transformer has spark
failure
Plug on fan not correctly plugged in, multiple plug on PCB not cor-
rectly plugged in, break in cable harness, fan blocked, Hall sensor
defective, electronics defective
Flue gas pressure cartridge: cable break, blocked flue gas route
Water pressure switch: hydraulic leak, air in heating circuit
Flue pipe blocked
Short circuit on eBUS, eBUS overload or two power supplies with dif-
ferent polarities on the eBUS
- Short circuit/short to earth in cable harness for the gas valve
- Gas valve defective (coils shorted to earth)
- Electronics defective
- Delayed shutdown of gas valve
- Delayed extinguishing of flame signal
- Gas valve leaking
- Electronics defective
Electronics defective
Flow or return NTC short circuited, electronics defective
Electronics overheating due to external influences, electronics
defective
Implausible flame signal, electronics defective
Spare parts case: Display and PCB replaced at the same time and
unit variant not reset
ecoTEC plus installation and maintenance instructions 0020134823_01