Buderus Logamax plus Service Manual page 10

3 Failures / Errors
4C
is flashing.
Overheat lock-out by temperatur limiters (2 x STB : Flue gas + prim. Heatexchanger). In this case ; Heat
demands is blocked and pump stops 3 minutes later.
Control Step
6. Electronic card is defect.
1) If the air inside not removed/discharged, can be also used the manuel air vent valve in recuparator.
10
Action
B Switch off the appliance.
B Cut mains supply.
B Change the electronic card.
B Connect to main supply.
B Switch on the appliance.
B END
GB012 - 25K