Vaillant ecoTEC VU 656/4 Installation And Maintenance Instructions Manual page 49

Code Meaning
F. 0 Interruption, flow temperature sensor
F. 1 Interruption, return temperature sensor
F.10 Short circuit flow sensor
F.11 Short circuit, return sensor
F.13 Short circuit cylinder sensor
F.20 Safety switch-off, temperature limiter
F.22 Safety switch-off, water shortage
F.23 Safety switch-off: temperature difference too great
F.24 Safety switch-off: temperature increase 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 Error, fan
F.49 Error, eBUS
F.61 Error, fuel valve control
F.62 Error, fuel valve switch-off delay
F.63 EEPROM error
F.64 Error, electronics/sensor
F.65 Error, temperature of electronics
F.67 Error, electronics/flame
F.70 Invalid boiler ID
F.71 Error, flow temperature sensor
Table 9.4 Fault codes (continued on next page)
Installation and maintenance instructions ecoTEC 0020029173_01
Cause
NTC plug not plugged in or has come loose, multiple plug on
electronics not plugged in correctly, interruption in cable harness,
NTC defective
NTC plug not plugged in or has come loose, multiple plug on
electronics not plugged in correctly, interruption in cable harness,
NTC defective
Short to ground/short circuit in cable harness, NTC defective
Short to ground/short circuit in cable harness, NTC defective
Short to ground/short circuit in cable harness, moisture in plug,
NTC defective
Incorrect earth connection between cable harness and boiler, flow
or return NTC defective (loose connection), black discharge via
ignition cable, ignition plug or ignition electrode
No or insufficient water in boiler, cable for pump, water pressure
sensor or volume flow sensor loose/not plugged in/defective, pump
blocked or defective, pump output too low, non-return valves
blocked/incorrectly installed, minimum quantity of circulation
water not reached, flow sensor defective
Pump blocked, insufficient pump output, air in appliance, system
pressure too low, flow and return NTC interchanged
Pump blocked, poor pump performance, air in boiler, installation
pressure too low, non-return valves blocked/incorrectly installed,
flow and return NTC mixed up
Break in plug connection for optional flue gas safety thermostat,
break in cable harness
Moisture on electronics, electronics (flame monitor) defective, gas
solenoid valve leaking
gas meter defective, gas pressure monitor has been triggered, air
in gas, gas flow pressure too low,
Thermal isolator device (TAE) has been triggered, condensate duct
blocked, incorrect gas throttle, error at gas valve, multiple plug on
electronics 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 boiler, electronics defective
Gas feed interrupted from time to time, flue gas recirculation,
condensate duct blocked, faulty earthing of boiler
Plug at fan not correctly plugged in, multiple plug on electronics
not correctly plugged in, break in cable harness, fan blocked, Hall
sensor defective, electronics defective
Short-circuit on eBUS input, eBUS overload or two power supplies
with different polarities on the eBUS
short circuit/short to ground in cable harness for gas valve, gas
valve defective (coils shorted to ground), 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 -
recirculation
Electronics too hot due to external effect, electronics defective
Implausible flame signal, electronics defective
Spare part case: Display and electronics changed at the same time
boiler variant not re-set
Flow temperature sensor signalling constant value -> flow
temperature sensor defective
Troubleshooting 9
49