Display shows E2 and unit cannot be programmed

Safety first: Disconnect power before working on the control panel.

• Check for physical damage: Inspect the keypad for stuck buttons, cracks, or signs of impact.
• Clean panel surface: Wipe the panel with a slightly damp cloth to remove dirt. Do not allow liquid to enter the panel.
• Inspect cable: Remove the front cover and verify that the keypad cable is firmly connected to the control board.
• Test buttons: Restore power and test each button. If some buttons do not respond or E2 remains, the keypad is likely defective.
• Replace keypad: Install a new Viessmann control panel / keypad assembly if cleaning and reseating do not resolve the issue.