Viessmann Vitotwin 300-W Installation And Service Instructions For Contractors page 126

Troubleshooting
Fault messages
Fault mes- Cause
sage
"164: Flow Flow sensor does not show
press switch any throughput.
HC"
"187: Con- Output configuration faults.
figuration
output"
"253: Fault Stirling burner or auxiliary
cause am- burner control unit have de-
biguous" tected a problem on start-up.
"254: Un- Fault without a defined fault
known error code.
code"
"257: Pack Short circuit or lead break to
sensor" internal appliance tempera-
ture sensor.
"258: Pack Internal appliance tempera-
overtem" ture exceeds maximum val-
ue.
"259: CJC Temperature sensor inside
sensor" the control unit reports a
fault.
126
(cont.)
Remedy
Check installation and con-
necting cable for flow sen-
sor.
Check the system pressure.
Vent the heating system.
Check whether there is any
throughput (code 8366 in di-
agnostics heat generation)
Check function of the circula-
tion pump.
Check function of 3-way
diverter valve.
Reconfigure system.
Check code 5700, reset if
necessary.
Check whether all connected
components (temperature
sensors, mixer extensions,
remote control unit etc.) have
been detected.
Carry out a service reset and
restart. If the fault has not
been rectified, replace the
control unit PCB (see
page 138).
Check connections to plug
X205. Check internal appli-
ance temperature sensor
(see page 145).
Check balanced flue system.
Ensure that flue gases are
not being recirculated.
Carry out a restart. If the fault
has not been rectified, re-
place the control unit PCB
(see page 138).
Re-
set-
ting
AR
SR
AR
SR