Bosch GWH-635-ES-N Manual page 27

Display Cause
E9 Temperature limiter opened circuit
(overheat).
EA No ionization during safety time (safety
time out).
FA Leakage error (gas valves do not close
gas circuit)
F7 Ionization error (flame sensing at stand-
by)
E0 Internal software/hardware failure.
A7 Hot water temperature sensor/receiver
defect (from main controller)
A9 Hot water temperature sensor/receiver
mis-assembled (from main controller)
E1 Over-temperature detected (from main
controller)
C1 FAN rotation too low at start-up (from
main controller)
C6 FAN rotation too low at operation (from
main controller)
C7 No rotational speed sensor signal from
FAN
CA Water flow signal over specified
maximum value
E2 Inlet temperature sensor fault
Table 5
* By installer or service technician only.
6 720 607 072 (16 January)
Solution
Check connections.*
Check gas pressure.
Check that gas is not diluted with air, as a
result from recent gas pipeline rework.*.
Check if vent terminal is blocked (specially
when the appliance starts up for some
seconds and then looses ionization signal).
Check ionization electrode.*
Check for a proper ground.*
Check gas valve and electronic controller.*
Check electronic controller.*
Check electronic controller.*
Check water temperature sensor/receiver and
connections.*
Check that the water temperature sensor/
receiver is properly assembled in the water
pipe.*
Check heat exchanger sealings.*
Check heat exchanger and flue gas collector.*
Check over temperature fuse.*
Check supply voltage.*
Check fan and connections.*
Check electronic controller.*
Check supply voltage.*
Check fan and connections.*
Check electronic controller.*
Check fan and connections.*
Check electronic controller.*
Check water valve and flow sensor.
Check water temperature sensor/receiver and
connections.*
Troubleshooting
27