Viessmann Vitodens 200-W Installation Instructions Manual page 140

Troubleshooting
Maintenance
Fault during commissioning (fault A3)
During commissioning, the control unit
checks correct placement of the flue gas
temperature sensor. If commissioning is
terminated and fault message A3 is dis-
played:
1. Check whether the flue gas temper-
ature sensor is correctly inserted.
See previous diagram.
Checking the fuse
A
1. Switch off the power.
2. Release the side closures and pivot
the control unit down.
140
(cont.)
2. If necessary, correct the position of
the flue gas temperature sensor or
replace faulty flue gas temperature
sensor.
3. Press reset button R and repeat com-
missioning.
The check is repeated until it is com-
pleted successfully.
F1
3. Remove cover A.
4. Check fuse F1 (see connection and
wiring diagram).