Thermostat displays E19 and may indicate 'Schedule memory error' or 'Timekeeping fault'; schedules may not run correctly.

Steps:

• Verify time settings: Check the thermostat's date and time. Correct them manually if wrong.
• Sync with app: Connect the thermostat to the Rheem app and enable automatic time synchronization if available.
• Factory reset schedules: Clear and reprogram schedules from the thermostat or app.
• Firmware update: Install any available firmware updates to address known RTC issues.
• If E19 continues and time drifts rapidly: The internal clock hardware is likely defective; thermostat replacement is recommended.