Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 139

Messages
(cont.)
Message
System characteristics Cause
B0 Device recognition
B1 KM BUS EEV
Error in recognising
appliance version, incor-
rect coding card or PCBs
faulty.
Communication fault
with EEV controller
(refrigerant circuit con-
trol), heat pump stage 1
(type BW)
Troubleshooting
Measures
■ Check sensor input F11
on the controller and
sensor PCB. No con-
nection should be made
at terminal F11.
■ Check coding card and
replace if required.
■ Check PCBs and
replace if required.
Check KM BUS connec-
tion. At the connection
between KM BUS and
EEV, a fluctuating DC
voltage between approx.
20 V and 30 V can be
measured at the controller
and sensor PCB at termi-
nals X5.14 and X5.15
(connections are parallel
to plug aVG).
Check leads/cables;
check power supply to
EEV controller PCB;
replace PCB if required.
139