Vaillant ecoTEC plus Instructions For Installation And Servicing page 43

Code Meaning
F.27 Incorrect sensing of flame
F.28 Appliance does not start: Attempts to ignite during start
failed
F.29 Flame goes off during operation and subsequent
F.32 Fan speed variation
F.49 eBUS under voltage
F.61 Gas–valve control defective
F.62 Gas valve shut off delay
F.63 EEPROM error
F.64 Electronics/NTC fault
F.65 Electronics temperature too high
F.67 Flame detector input signal is outside the limits (0 or 5
V)
F.70 No valid DSN in display and/or main board
F.71 Flow NTC reports constant value (stuck at)
F.72 Flow and/or return NTC fault
F.75 No pressure rise was detected on turning on the pump
F.76 Overheating protection on primary heat exchanger
triggered
F.77 Condensate pump or feedback of accessories blocks
heating
F.78 Wrong configuration with accessory
con No communication to main board
Table 10.4 Error codes (continued)
Installation and Servicing ecoTEC plus
Cause
Flame detector defective
Faults in the gas supply such as:- - Gas meter or gas pressure
detector defective - Air in gas- Gas flow pressure too low - Fire
protection tap has disengaged Faults in the gas valve, wrong
gas setting, igniter (ignition transformer, ignition cable, ignition
plug) defective, ionisation current stopped (cable, electrode),
faulty earthing in appliance, electronics defective
ignition attempts failed Gas supply temporarily stopped, faulty
earthing of appliance
Fan blocked, plug not inserted correctly on fan, hall sensor
defective, fault in cable harness, electronics defective
Short circuit on eBUS, overload on eBUS or two power sources
on eBUS with different polarity
Short circuit/earth (ground) leak in cable harness to gas valves,
gas valve assembly defective (earth/ground leak from coils),
electronic control system defective
Gas valve leaking, electronics defective
Electronics defective
Short-circuit in flow or return NTC or electronics defective
Electronics too hot due to external effect, electronics defective
Electronics defective
Spare part failure display and main board interchanged at
same time and device specific number not adjusted
Flow NTC is defective
Flow and/or return NTC is defective (tolerances too big)
Water pressure sensor or/and pump defective Air in the heating
system, quick bleeder defective Too little water in appliance;
check adjustable by-pass; connect external expansion vessel to
return
Cable or cable connection of fuse in the primary heat
exchanger defective, or primary heat exchanger defective
Condensate pump defective or flume flap feedback triggered
link box VR65 connected to combination boiler
Connection error display main board
Troubleshooting 10
43