Boulter Buderus Benchmark 600-28C Installation And Servicing Instruction page 41

Servicing
Code Meaning
4L Blinking fault code: Wiring or connections or sensor exceeds 130 °C
Possible
cause
1 Resistance in the installation is too high
2 Water pressure is too low in the installation
3 Problem with the pump or pump cabling
(no circulation)
4 Bi-sensor is dirty or faulty
Code Meaning
4P Blinking fault code: Bi-sensor has a loose connection or is defective
Possible
cause
1 Bi-sensor faulty or disconnected
2 A short or bad connection in the cable harness
3 UBA might be faulty
Code Meaning
4U Blinking fault code: Short circuit in bi-sensor
Possible
cause
1 Bi-sensor is dirty or faulty
2 A short or bad connection in the cable harness
3 UBA might be faulty
Code Meaning
4Y
Blinking fault code: Bi-sensor interrupted
Possible
cause
1 Bi-sensor faulty or disconnected
2 A short or bad connection in the cable harness
3 UBA might be faulty
Subject to modifications resulting from technical improvements!
Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 28C • 01/2004
Action
Check if not all (thermostatic) radiator valves are closed or
clogged with dirt
Top up the system (see subsection 2.1.1)
Check if the pump cabling is faulty or if the pump is stuck.
Replace pump when necessary (see subsection 5.3.6 and
subsection 5.3.7)
Check the bi-sensor for dirt. Measure if resistance over the
sensor is correct. If not replace bi-sensor (see subsection
5.3.8, subsection 5.3.9, subsection 5.3.10)
Action
Check the sensor and measure if resistance over the
sensor is correct. If not replace bi-sensor (see subsection
5.3.8, subsection 5.3.9, subsection 5.3.10)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.2)
Action
Check the sensor, replace when necessary
(see subsection 5.3.8 and subsection 5.3.9)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.2)
Action
Check the sensor and measure if resistance over the
sensor is correct. If not replace bi-sensor (see subsection
5.3.8, subsection 5.3.9, subsection 5.3.10)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.2)
Boulter Buderus Ltd. • http://www.boulter-boilers.com
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