Thermostat shows E18 and indicates an internal clock or time sync error.

Safety note: No mains work is required unless the thermostat must be removed.

Steps to resolve:

• 1. Check internet connection: If the thermostat syncs time via the internet, ensure Wi‑Fi and cloud connectivity are working.
• 2. Manually set time: Use the thermostat menu to manually set the correct time and date. Monitor if it drifts or resets.
• 3. Firmware update: Update to the latest firmware via the Baxi app to correct any known RTC issues.
• 4. Replace batteries (if applicable): For models with internal backup batteries, replace them with new ones.

When to call a professional: If the clock cannot keep time even after these steps, the internal RTC hardware is likely faulty and the thermostat should be replaced.