Viessmann VITOCAL 242-G Installation And Service Instructions Manual page 126

Troubleshooting
Control unit diagnostics
Fault messages
38 Primary in
sensor
40 Heating circuit
2 flow sensor
(mixer circuit)
44 Natural cool-
ing flow sen-
sor
48 Heating circuit
2 flow sensor
4C Natural cool-
ing flow sen-
sor
50 DHW sensor
top
52 DHW sensor
bottom
58 DHW sensor
top
5A DHW sensor
bottom
60 Buffer cylinder
sensor
61 Secondary re-
turn sensor
68 Buffer cylinder
sensor
69 Secondary re-
turn sensor
92 Solar collector
sensor
93 Solar return
sensor
9A Solar collector
sensor
9B Solar return
sensor
A4 Check valve
126
(cont.)
Cause
Lead broken
Short circuit
Lead broken
Short circuit
Lead broken
Short circuit
Lead broken
Short circuit
Lead broken
The check valve is stuck or
faulty; the solar circuit cir-
culates during the night
Measures
Check the terminals and re-
place the sensor, if required
Check the sensor and re-
place, if required
Check the terminals and re-
place the sensor, if required
Check the sensor and re-
place, if required
Check the terminals and re-
place the sensor, if required
Check the sensor and re-
place, if required
Check the terminals and re-
place the sensor, if required
Check the sensor and re-
place, if required
Check the terminals and re-
place the sensor, if required
Check the check valve and
replace, if required