F.70 — Invalid device specific number (DSN)

What does F.70 mean?

This fault typically occurs after replacement of both the display and the main PCB, where the appliance code (DSN) was not correctly reset by the installer.

• Display and PCB were replaced simultaneously, and the appliance code was not reset.
• Incorrect configuration after a spare part installation.

Click steps to track your progress.

1. 1

   Press the fault clearance key on the boiler to reset it.

2. 2

   Note the fault code and report it to your heating engineer or Vaillant Service Solutions.

3. 3

   This usually requires an installer to reset the appliance code (D.094) at the installer level.