Problem solving
69
C 950/C 1050 (Pro TL 175 C/199 C) – 6 720 805 440 (2019/10)
Table 54 * By installer or service technician only.
F1 Parameter in memory not found
1. Replace ECU (Electronic Control Unit) if there are repeated errors.
F2 Internal Operations error
F3 Internal memory parameter
error
F4 Internal memory error
F5 Analog test fail
F6 Gas type parameter error
E7 Appliance parameter not
defined
F0 Burner Control routine state
error
E5 Burner Control error
E6 Burner Control routine check
sum error
F8 Fan stopping error 1. Check primary fan cable harness
2. Check fan rotation in standby
3. Check proper function of primary fan
4. Replace ECU (Electronic Control Unit)
F9 Gas Control error 1. Check Gas Valve cable harness (connection to gas valve and to ECU)
2. Check Gas Valve (Replace if necessary)
3. Replace ECU (Electronic Control Unit)
F7 Ionization error at standby. 1. Loose connection to the flame ionization rod. Verify that the thinner wire leading
from the control unit is securely connected to the set of electrodes located on the
lower front of the heat exchanger.
2. Flame ionization rod or control unit may be damaged. Contact Bosch Water
Heating for further instruction.
FA Gas leakage error, gas valve
circuit not closing properly.
1. Disconnect power supply cord and check wire connections on gas valve and the
two connectors on the control board.
2. Flow water out of a hot water tap above the minimum activation point of 0.5 GPM.
Measure voltage at the gas valve wire plug connection. The voltage should measure
24VDC between the left pair of wires and 24VDC between the right pair of wires
when the unit is operating. If voltage is not proper, contact Bosch Water Heating for
further instruction.
3. Gas valve may be defective, contact Bosch Water Heating for further instruction.
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