Ab Error - Bosch Singular 4000 Service Manual

Service Manual
8.10 AB Error (Abnormal Operation: Heat Exchanger Temperature Sensor
Error
Hex Thermistor_T2 error
Checkpoint
Figure 33
Figure 34
3 4 |
Description
Error is displayed when the Heating water sensor has short-circuited or is disconnected
 Check if the Hex Thermistor connector is connected normally.
1. Control board wire
2. Heating water sensor wire
 Measure and check the resistance of the heating water sensor (NTC method).
Separate the sensor and measure it at room temperature.
—
 Check the heating water sensor for disconnection
 Check the heating water sensor for short-circuit
Check the assembly
condition of the control board
and the temperature sensor
connector and reassemble
the control board and the
temperature sensor connector
Check the
temperature
sensor for short
Yes
Is the
resistance of the
temperature sensor
normal?
Yes
Replace the control board
No
Replace the temperature
sensor
No
Replace the temperature
sensor
86 °F: 40 kΩ (± error possible)
140 °F: 12.4 kΩ
185 °F: 3.9 kΩ
Singular Combi Boiler - BTC 439002301 A (12.2021)