Bosch CW 800 - Faults you can fix yourself

6 720 820 871 (2016/12)CR 400 | CW 400 | CW 800
Eliminate fault | 45
Faults you can fix yourself
If an operating fault cannot be rectified:
▶ Contact an authorised installer, or customer service.
Submit error code, additional code and control unit ID
number.
Fault code Sub- code
Cause or fault
description
Test procedure / Cause Action
Nothing appears on the display System is switched off. ▶ Switch on the system.
The power supply to the user interface has been
interrupted.
▶ Check that the user interface is
correctly seated in its wall
mounting bracket.
A01 810 DHW stays cold. Check if water is possibly being drawn from the
DHW cylinder constantly due to taps being open.
▶ If water is being drawn
constantly, take action to stop
this.
A01 811 DHW heating: thermal
disinfection failed
Check if water is possibly being drawn from the
DHW cylinder constantly due to taps being open.
▶ Take action to stop water being
drawn constantly.
A11 1010 No communication via
BUS connection EMS 2
– ▶ Check that the user interface is
correctly seated in its wall
mounting bracket.
A11 1038 Invalid time/date Date/time not yet set ▶ Set date/time.
Prolonged loss of power supply ▶ Avoid voltage failures.
A11 3061
...
3068
No communication with
heating circuit module
(3061: heating
circuit 1, ..., 3068:
heating circuit 8)
– ▶ Check that the user interface is
correctly seated in its wall
mounting bracket.
A11 6004 No communication w.
solar module
– ▶ Check that the user interface is
correctly seated in its wall
mounting bracket.
A21
...
A28
1001 – No BUS connection between C 400/C 800 and
CR10 or CR100 in the corresponding heating
circuit (A21: heating circuit 1, ..., A28: heating
circuit 8).
▶ Check that the user interface is
correctly seated in its wall
mounting bracket.
A41
A42
4051
4052
Thermal disinfection
failed.
Check if water is possibly being drawn from the
DHW cylinder constantly due to taps being open.
▶ Take action to stop water being
drawn constantly.
H... – – Maintenance required. The system keeps
operating as far as possible.
▶ Make arrangements to have the
system serviced by your
contractor.
H07 1017 – Water pressure in the system is too low. This
value is only displayed if your system is
equipped with a digital pressure sensor.
▶ Top up the heating water as
described in the operating
instructions of the heat source.
Table 40
__ _
Table 41 The control unit ID number must be filled in here by the installer at installation.