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Service Manual
Singular Combi Boiler - BTC 439002301 A (12.2021)
8.8 A9 Error (Exhaust Temperature Sensor Error)
Error Description
Exhaust temperature
sensor error
F
reeze prevention error due to a temperature decrease of the heating water
— Heating water temperature <= 43 °F: Combustion in progress
— Heating water temperature >= 104 °F: Combustion stopped
Checkpoint
Check if the heating water temperature is <= 43 °F
Check if the heating water sensor connection is OPEN
Check the resistance of the heating water sensor
Table 30
Figure 28
Check the assembly of
the heating water sensor
connector and reassemble it
Replace the temperature
sensor
Operated when
the heating water
temperature is
<=42 °F
Is the
temperature sensor
resistance normal?
Ye s
Ye s
No
No
86 °F: 40 kΩ
140 °F: 12.4 kΩ
185 °F: 3.9 kΩ
Replace the control board
Replace the control board
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