Thermostat displays E12 and time or date cannot be set or keeps reverting

Safety first: No special electrical risk beyond normal thermostat handling.

• Sync via app: If supported, connect the thermostat to Wi‑Fi and allow it to synchronise time automatically from the internet. This can bypass a weak internal clock.
• Firmware update: Check in the app or Vokera support site for any firmware updates that address timekeeping issues.
• Minimise power cuts: Ensure the thermostat is not on a frequently switched spur or extension that is turned off nightly.
• If E12 persists and schedules misfire: Replace the thermostat, as the RTC hardware is likely defective.