Vaillant ecoTEC plus VUI Series Installation And Maintenance Instructions Manual page 78

Code/meaning
F.044
The ionisation signal for the
control electrode is too low. The
drift adaptation has failed.
F.047
The signal for the domestic hot
water temperature sensor at the
output for the internal cylinder is
implausible.
F.049
The eBUS has short-circuited or
two active eBUS sources have
inverted polarity.
F.057
The combustion regulation has
failed and the associated limp
home mode has failed.
F.061
The ASIC or µControl does not
run in the defined times.
F.062
The flame switch-off was detec-
ted after a delay.
F.063
EEPROM reports faults during
the read/write test.
78
Possible cause
Interruption in the wiring har-
ness
Burner defective
Gas valve assembly defect-
ive/incorrect spare part gas
valve assembly
Gas valve assembly offset in-
correctly stored in D.052 und
ggf. D.182
Control electrode defective
Gas valve defective
PCB defective
Fault in the electronic connec-
tion for the cylinder outlet tem-
perature sensor
Cylinder outlet temperature
sensor defective
Short circuit in the eBUS con-
nection
Different polarities at the eBUS
connection
PCB defective
Limp home mode failed
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
Gas valve assembly offset in-
correctly stored in D.052 und
ggf. D.182
Interruption in the wiring har-
ness
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)
Fault in the electrical connection
for the gas valve assembly
PCB defective
Gas valve defective
PCB defective
Ignition electrode defective
PCB defective
Measure
▶
Check the wiring harness including all plug connections and, if
required, replace it.
▶
Check and, if required, replace the burner.
▶
Check and, if required, replace the gas valve assembly.
▶
Check the offset setting for the gas valve assembly.
▶
Check and, if required, replace the control electrode.
▶
Replace the gas valve.
▶
Replace the PCB.
▶
Check the wiring harness between the PCB and sensor, in-
cluding all plug connections.
▶
Replace the cylinder outlet temperature sensor.
▶
Check all eBUS connections.
▶
Check the polarity (±) of the eBUS connections.
▶
Replace the PCB.
▶
Check the limp home mode and fault history, and carry out the
required measures.
▶
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 offset setting for the gas valve assembly.
▶
Check the wiring harness including all plug connections and, if
required, replace it.
▶
Replace the PCB.
▶
Use D.033 and D.034 to check whether the fan speed deviates
by more than 20–30 rpm.
1. Check the air-mass flow sensor for dirt.
2. If required, replace the entire air intake pipe.
▶
Check and, if required, replace the wiring harness for the gas
valve assembly.
▶
Replace the PCB.
▶
Replace the gas valve.
▶
Replace the PCB.
▶
Check and, if required, replace the ignition electrode.
▶
Replace the PCB.
Installation and maintenance instructions 0020308121_04