Vaillant · ecoTEC plus Boilers
This fault indicates that the external current anode is either not connected, or its power supply has been interrupted. This is relevant if an external current anode is installed.
Click steps to track your progress.
If an external current anode is NOT installed, ensure the X43 edge connector with the bridge is present on the PCB.
If an external current anode IS connected, check its power supply for interruptions.
Inspect the cable between the PCB and the external current anode for damage.
If issues persist, the external current anode itself may be defective (contact a technician).