Boulter Buderus Benchmark 600-28C Installation And Servicing Instruction page 44

5 Servicing
Code Meaning
9A; 9H; Blinking fault code: System error
9U; P
Possible
cause
1 UBA not placed correctly
2 UBA may be defective
3 KIM may be defective action
Code Meaning
9L Blinking fault code: Gas valve assembly error
Possible
cause
1 Wiring to the gas valve incorrect, or loose wiring
connections in UBA
2 UBA may be defective
3 KIM may be defective
Code Meaning
CA Blinking fault code: Return sensor exceeds 105 °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 Return sensor is dirty or faulty
Code Meaning
CO Blinking fault code: Pressure sensor fault
Possible
cause
1 Wiring and connections of the pressure sensor may be
faulty
2 Pressure sensor may be faulty
Subject to modifications resulting from technical improvements!
44 Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 28C • 01/2004
Action
Check to see if UBA is securely mounted
(see subsection 5.3.2)
Press reset. If fault code remains then try to temporarily
connect a different UBA (see subsection 5.3.2)
Call the service department of Boulter Buderus
Action
– Check the electrical connections of the gas valve.
– Measure the resistance of the gas valve
– Check if for example induction fields interfere with the
regulating device
Press reset. If fault code remains then try to temporarily
connect a different UBA (see subsection 5.3.2)
Call the service department of Boulter Buderus
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 return sensor for dirt.
Measure if resistance over the sensor is correct.
If not replace return sensor (see subsection 5.3.8)
Action
Check the wiring and connection of the pressure sensor
Check the pressure sensor and replace when necessary
Boulter Buderus Ltd. • http://www.boulter-boilers.com