Vaillant ecoTEC plus VUI Series Installation And Maintenance Instructions Manual page 77

Code/meaning
F.035
The air/flue pipe is blocked.
F.040
The air ratio is too low.
F.042
The coding resistor (in the wir-
ing harness) or the gas group
resistor (on the PCB, if avail-
able) is invalid.
F.044
The ionisation signal for the
control electrode is too low. The
drift adaptation has failed.
0020308121_04 Installation and maintenance instructions
Possible cause
Condensate pump (if fitted)
defective
Insufficient combustion air sup-
ply
Control electrode defective
Burner defective
Gas valve assembly defect-
ive/incorrect spare part gas
valve assembly
Fault in the flue gas route
caused by recirculation or flue
gas blockage
Air intake pipe blocked
Condensate in the combustion
chamber due to a blocked con-
densate discharge
Condensate pump (if fitted)
defective
Incorrect gas type set
Gas valve assembly offset in-
correctly stored in D.052 und
ggf. D.182
Fault in the electrical connection
for the gas valve assembly
Gas valve assembly not elec-
trically connected/incorrectly
connected
Control electrode defective
Burner defective
PCB defective
Fan defective
Air-mass flow sensor dirty or
defective (only in conjunction
with the conversion set compris-
ing the air intake pipe with in-
tegrated non-return valve and
air-mass flow sensor)
Interruption in the wiring har-
ness to the gas valve assembly
Fault in the flue gas route
caused by recirculation or flue
gas blockage
Air intake pipe blocked
Condensate in the combustion
chamber due to a blocked con-
densate discharge
Condensate pump (if fitted)
defective
Gas flow pressure too low
Incorrect gas type set
Measure
▶
Check and clean the condensate pump. Replace the condens-
ate pump, if required.
▶
Check the combustion air supply.
▶
Check and, if required, replace the control electrode.
▶
Check and, if required, replace the burner.
▶
Check and, if required, replace the gas valve assembly.
▶
Check the entire flue gas route.
▶
Check and, if required, replace the air intake pipe.
1. Check and, if required, clean the condensate discharge pipe
including the siphon.
2. Check the combustion chamber (electrodes, insulating mats,
burner).
3. If required, replace the insulating mats in the combustion
chamber.
▶
Check and clean the condensate pump. Replace the condens-
ate pump, if required.
▶
Check the gas type and the gas type setting under D.156 and
D.157.
▶
Check the offset setting for the gas valve assembly.
▶
Check and, if required, replace the wiring harness for the gas
valve assembly.
▶
Check the electrical connection to the gas valve assembly.
▶
Check and, if required, replace the control electrode.
▶
Check and, if required, replace the burner.
▶
Replace the PCB.
▶
Check and, if required, replace the fan.
1. Check the air-mass flow sensor for dirt.
2. If required, replace the entire air intake pipe.
▶
Check the wiring harness between the PCB and gas valve
assembly, including all plug connections (especially on the
PCB).
▶
Check the entire flue gas route.
▶
Check and, if required, replace the air intake pipe.
1. Check and, if required, clean the condensate discharge pipe
including the siphon.
2. Check the combustion chamber (electrodes, insulating mats,
burner).
3. If required, replace the insulating mats in the combustion
chamber.
▶
Check and clean the condensate pump. Replace the condens-
ate pump, if required.
▶
Check the gas flow pressure and the external gas pressure
switch.
▶
Check the gas type and the gas type setting under D.156 and
D.157.
77