Thermostat shows E6 and cannot save new schedules or settings

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Flash memory wear-out on thermostat PCB, Firmware corruption, Power loss during previous firmware update, Manufacturing defect in memory chip

Safety: No mains work required.

Factory reset: Perform a full factory reset from the thermostat menu. Reconfigure Wi‑Fi, schedules, and boiler pairing afterward.
Firmware reinstall: If the app offers a firmware repair or reinstall option, run it while the thermostat is connected to stable power and Wi‑Fi.
Avoid power cuts: Do not interrupt power during any update or reset process.

If E6 remains and settings are not retained after power cycles, the internal memory is defective and the thermostat must be replaced.

Medium 3/5

Saunier Duval Smart Thermostat Main PCB (Flash Memory)

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