Viessmann B1HE-120 - Page 74

74
6167 818 - 10
Vitodens 100-W, B1HE/B1KE Combi Installation/Service
Fault Messages
(continued)
Troubleshooting
Displayed
fault code
System characteristics Cause Measures
F.70 Burner in a fault state Internal error burner
control unit
Replace BCU burner control unit:
See page 89.
F.71 Burner in a fault state Fan speed too low
 Check fan for blockage.
 Check the gas type and flue system setting in the
commissioning assistant and correct if necessary.
Reset the boiler.
F.72 Burner in a fault state Fan idle state not
reached
Reset the boiler.
If fault occurs repeatedly, replace fan unit.
F.73 Burner in a fault state Internal
communication error
Reset the boiler.
If fault recurs, replace BCU burner control unit:
See page 89.
F.74 Burner locked out.
Internal circulation pump
off.
No central heating and
no DHW heating.
Water pressure too
low
Top up with water.
Vent the system.
If the fault occurs repeatedly:
 Check system pressure sensor with external manometer.
 Check diaphragm expansion tank pre-charge
pressure.
 Check settings for target system pressure and range.
F.77 Burner in a fault state Data memory burner
control unit
Reset the boiler.
If fault recurs, replace BCU burner control unit:
See page 89.
F.89 No central heating and
no DHW heating
Internal circulation
pump blocked
Check circulation pump.
Replace if necessary.
F.142 Burner in a fault state Communication error
CAN bus
 Check the fan unit for correct function. For this,
check the stepper motor of the fan unit (reference
run with mains ON).
 If the fault still persists, visually check the plug-in
connections and cables of the CAN bus.
 Check further CAN bus subscribers.
If fault still persists, replace the fan unit.
F.160 Burner in a fault state Communication
error CAN bus
 If “Connection error” is displayed, check the internal
CAN bus subscriber connections.
 If only F.160 is displayed, check the connections of
the external CAN bus subscribers.
 Check the connecting cables for firm seating and
corrosion.
Reset the boiler.
F.161 Burner in a fault state BCU data memory
access error
Reset the boiler.
If fault recurs, replace BCU burner control unit:
See page 89.
F.163 Burner in a fault state Memory access
checksum error BCU
Reset the boiler.
If fault recurs, replace BCU burner control unit:
See page 89.