Viessmann WB2-44 - Page 37

Troubleshooting
37
Cause of fault Corrective action
Emissions test switch ”S” turned to ”h” for 30 minutes
already.
Turn emissions test switch ”S”to”a”.
Setting mode for maximum or minimum rated input active
for 30 minutes already.
Set heating program selector switch to required operating
mode or close cover on programming unit.
Reset button ”EU” pressed while burner is off with emis-
sions test switch ”S” turned to ”h”.
Turn emissions test switch ”S”to”a” and press reset
button ”EU” once.
Basic level of air pressure threshold in standby mode not
correct.
Check differential air pressure sensor (see page 41).
Check wiring harness and connection to air pressure sensor.
Fault will clear if output signal of air pressure sensor is
correct.
Start-up prevented. Check wiring, water and gas pressures.
DHW outlet sensor / short circuit Check sensor/wiring.
See coding address “000” (page 49).
See coding address “0B8” (page 54).
DHW outlet sensor / open circuit Check sensor/wiring.
See coding address “000” (page 49).
See coding address “0B8” (page 54).
5285 961 v1.3