Viessmann B0KA - Page 68

68
Displayed fault
code
System characteristics Cause Measures
386 Burner in a fault state HBMU heat management
unit faulty
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Reset the appliance.
387 Burner in a fault state Ionisation current earth
fault, HBMU heat man-
agement unit faulty.
Check ionisation electrode and
connecting cable. If the fault per-
sists, replace the HBMU heat man-
agement unit. See chapter "Re-
placing the HBMU heat manage-
ment unit".
Reset the appliance.
388 Burner in a fault state HBMU heat management
unit faulty
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Reset the appliance.
393 Burner in a fault state Short circuit, flue gas tem-
perature sensor 2.
Check flue gas temperature sensor
2 and leads to sensor.
Reset the appliance.
394 Burner in a fault state Lead break, flue gas tem-
perature sensor 2.
Check flue gas temperature sensor
2 and leads to sensor. Replace
sensor if necessary.
Reset the appliance.
399 Burner in a fault state IO electrode earth fault,
HBMU heat management
unit faulty
Check IO electrode for earth fault.
If the fault persists, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
Reset the appliance.
400 Burner in a fault state HBMU heat management
unit faulty
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Reset the appliance.
401 Burner in a fault state IO electrode earth fault,
HBMU heat management
unit faulty
Check IO electrode for earth fault.
If the fault persists, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
Reset the appliance.
402 Burner in a fault state HBMU heat management
unit faulty
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Reset the appliance.
403 Burner in a fault state Ionisation electrode earth
fault, HBMU heat man-
agement unit faulty
Check IO electrode for earth fault.
If the fault persists, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
Reset the appliance.
404 Burner in a fault state HBMU heat management
unit faulty
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Reset the appliance.
Troubleshooting
Fault messages (cont.)
6179762
Diagnosis