Bosch OptiFlow Professional GWH12 1 CTD E23, Operating Manual

Page: 9 / 16

6 720 813 939 (2016/05) OptiFlow Professional
Troubleshooting | 9
5 Troubleshooting
Fitting, maintenance and repair must only be carried out by authorised technicians. The following table describes the possible
solutions.
Display Description Possible solution
A0 Cold and hot water temperature sensor damaged. ▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
A1 Temperature inside the water heater housing is high
(heat exchanger calcified or sooted). ▶ The appliance automatically regulates its
performance to avoid overheating.
▶ If the problem persists, call an authorised
service technician.
A4 Faulty air temperature sensor. ▶ Call an authorised service technician.
A7 Faulty hot water outlet temperature sensor. ▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
A9 Hot water outlet temperature sensor is not fitted
properly.
Low incoming gas pressure.
▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
C7 Faulty fan. ▶ Check if the fan is properly connected to
ECU.
▶ If the problem persists, call an authorised
service technician.
CA Water flow above maximum specified value. ▶ Check incoming water pressure.
▶ Install a pressure limiting valve if necessary.
CF
C1
Blocked flue gas outlet.
Air flow insufficient for start-up.
▶ Remove dirt or any other impediment from
the flue terminal and/or pipe.
▶ Close and open a hot water tap.
▶ If the problem persists, call an authorised
service technician.
E0 Failure of control module ▶ Unplug the electrical connection for 10
seconds.
▶ Reconnect and restart the appliance.
▶ If the problem persists, call an authorised
service technician.
E1 Hot water temperature sensor detects overheating. ▶ Let the appliance cool and try again.
▶ If the problem persists, call an authorised
service technician.
Table 4