Buderus 600 - 11S Installation And Maintenance Instructions Manual page 39

Code Meaning
4L
Short circuit in safety sensor
Possible
cause
1 Safety sensor is faulty
2 A short or bad connection in the cable harness
3 UBA might be faulty
Code Meaning
4P
Safety sensor has a loose connection or is defective
Possible
cause
1 Safety sensor faulty or disconnected
2 A short or bad connection in the cable harness
3 UBA might be faulty
Code Meaning
4U
Short circuit in flow sensor
Possible
cause
1 Flow sensor is dirty or faulty
2 A short or bad connection in the cable harness
3 UBA might be faulty
Code Meaning
4Y
Flow sensor interrupted
Possible
cause
1 Flow 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 - 11S/19S/24S/24C • 02/2006
Action
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)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Action
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)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Action
Check the sensor, replace if necessary (see subsection
5.3.14, subsection 5.3.15, subsection 5.3.16)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Action
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)
Check the cable harness and/or connector of the sensor
Check the UBA by temporarily connecting a different UBA
(see subsection 5.3.3)
Buderus • http://www.buderus-domestic.co.uk
Servicing 5
39