Troubleshooting - Bosch OptiFlow Professional GWH12 1 CTD E23 Operating Manual

10 | Troubleshooting

5 Troubleshooting
Fitting, maintenance and repair must only be carried out by authorised technicians. The following table describes the possible
solutions.
Display
A0
A1
A4
A7
A9
C7
CA
CF
C1
E0
E1
Table 4
6 720 813 938 (2016/06)
Description
Cold and hot water temperature sensor damaged.
Temperature inside the water heater housing is high
(heat exchanger calcified or sooted).
Faulty air temperature sensor.
Faulty hot water outlet temperature sensor.
Hot water outlet temperature sensor is not fitted
properly.
Low incoming gas pressure.
Faulty fan.
Water flow above maximum specified value.
Blocked flue gas outlet.
Air flow insufficient for start-up.
Failure of control module
Hot water temperature sensor detects overheating.
Possible solution
▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
▶ The appliance automatically regulates its
performance to avoid overheating.
▶ If the problem persists, call an authorised
service technician.
▶ Call an authorised service technician.
▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
▶ Check if the fan is properly connected to
ECU.
▶ If the problem persists, call an authorised
service technician.
▶ Check incoming water pressure.
▶ Install a pressure limiting valve if necessary.
▶ 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.
▶ Unplug the electrical connection for 10
seconds.
▶ Reconnect and restart the appliance.
▶ If the problem persists, call an authorised
service technician.
▶ Let the appliance cool and try again.
▶ If the problem persists, call an authorised
service technician.
OptiFlow Professional