Buderus Logamax GB062-24 KDE H V2 Service Manual page 18

4
Fault finding
5L
BUS-Communication fault
Step
1. B Switch off the boiler.CP
B Cut the main voltage supply.
B Check the connection terminals at
controls and boiler.
Are the connection terminals dirty or
corroded ?
2. B Check the connections between the
control (thermostat) and the boiler.
Is resistance very high ?
3. Electronic board (PCB) is defect.
18
Remedy
yes: B Clean the connection terminals.
B Connect the cable again.
B Switch on the boiler.
5L on display ? --> 2.
no: B Remove the control (thermostat) and check the
error again. If there is no error, check the control
(thermostat). Change if necessary, change it.
B Switch on the boiler.
--> 2.
yes: B Switch on the boiler.
B Cut the main voltage supply.
B Change the connection cable between boiler and
control (thermostat).
B Switch on the boiler.
5L on display ? --> 2.
no: --> 3.
B Switch off the boiler.
B Cut the main voltage supply.
B Change the electronic board (PCB).
B Switch on the main voltage supply.
B Switch on the boiler.
B END
Logamax Plus GB062