Bosch Singular 4000 - Page 47

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Service Manual
Singular Combi Boiler - BTC 439002301 A (12.2021)
E2 Error - Wire Check
1. Check the connection of the wire.
Figure 66 Control Board
Figure 67 Exhaust Temp. Sensor
E2 Error - Exhaust Temperature Sensor Check
1. Measure the resistance of the Exhaust Temp. Sensor.
— If the resistance is not normal, replace the Exhaust Temp. Sensor.
Figure 68
KΩ
E2 Error - Disconnection Check
1. Check if the Exhaust Temp. Sensor is disconnected.
— Disconnection: OL
— Normal: 86 °F: 7.05 kΩ
140 °F: 2.5 kΩ
201 °F: 952 Ω
Figure 69
kΩ
E2 Error - Short Circuit Check
1. Check if the Exhaust Temp. Sensor has short-circuited.
— Short circuit: 0 Ω
— Normal: 86 °F: 7.05 kΩ
140 °F: 2.5 kΩ
201 °F: 952 Ω
Figure 70
Ω
E2 Error - Control Board Check
1. If the wire connection and the resistance of the Exhaust Temp. Sensor are
normal, replace the control board.