Viessmann VITODENS 300 WB3A, Service Instructions Manual

Page: 94 / 148

Displayed
fault code Const. Weat-
her-
comp. System
character-
istics Cause Remedy
94 X X Control
mode Solar: Cylinder
temperature sensor
shorted out Check sensor
9C X X Cylinder tempera-
ture sensor lead
break
9F X X Control
mode Solar control unit
fault message See solar
control unit
service
instructions
A7 X Control
mode Faulty operating
interface Replace
operating
interface
b0 X X Burner
blocked Flue gas tempera-
ture sensor short
circuit Check the
flue gas tem-
perature sen-
sor (see
page 88)
b8 X X Flue gas tempera-
ture sensor break
b1 X X Control
mode Communication
fault
–
program-
ming unit (internal)
Check con-
nections and
replace the
programming
unit, if neces-
sary
b4 X X Emissions
test mode Internal fault ana-
log converter Replace con-
trol unit
b5 X X Control
mode Internal fault Replace con-
trol unit
b7 X X Burner
blocked Boiler coding card
missing, faulty or
incorrect card
inserted Plug in the
boiler coding
card or
replace, if
faulty
Checking and acknowledging faults
(cont.)
78
Troubleshooting
56
92
550
GB