Servicing
5
Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 11S/19S/24S/24C • 02/2006
39
Subject to modifications resulting from technical improvements!
Buderus • http://www.buderus-domestic.co.uk
Code
Meaning
4L
Short circuit in safety sensor
Possible
cause
Action
1
Safety sensor is faulty
Check the sensor and measure if resistance over the
sensor is correct. If not replace safety sensor (see
subsection 5.3.11, subsection 5.3.12, subsection 5.3.13)
2
A short or bad connection in the cable harness
Check the cable harness and/or connector of the sensor
3
UBA might be faulty
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Code
Meaning
4P
Safety sensor has a loose connection or is defective
Possible
cause
Action
1
Safety sensor faulty or disconnected
Check the sensor and measure if resistance over the
sensor is correct. If not replace safety sensor (see
subsection 5.3.11, subsection 5.3.12, subsection 5.3.13)
2
A short or bad connection in the cable harness
Check the cable harness and/or connector of the sensor
3
UBA might be faulty
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Code
Meaning
4U
Short circuit in flow sensor
Possible
cause
Action
1
Flow sensor is dirty or faulty
Check the sensor, replace if necessary (see subsection
5.3.14, subsection 5.3.15, subsection 5.3.16)
2
A short or bad connection in the cable harness
Check the cable harness and/or connector of the sensor
3
UBA might be faulty
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Code
Meaning
4Y
Flow sensor interrupted
Possible
cause
Action
1
Flow sensor faulty or disconnected
Check the sensor and measure if resistance over the
sensor is correct. If not replace safety sensor (see
subsection 5.3.14, subsection 5.3.15, subsection 5.3.16)
2
A short or bad connection in the cable harness
Check the cable harness and/or connector of the sensor
3
UBA might be faulty
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)