115
Ariston
Display Backlight / LCD Power Failure
Thermostat shows error 115 and the display is very dim or completely blank, though the boiler still runs on its own controls.
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Safety Warning
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.
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Possible Causes
Faulty LCD backlight driver, Loose display ribbon cable, Power supply fault on thermostat PCB, Overvoltage damage
How to Fix / Troubleshooting
Safety: Isolate power to the thermostat before opening it.
- Check for life: Press buttons and see if the boiler responds (e.g. heating demand LED on boiler). If control works but screen is dark, the issue is display-related.
- Inspect connections: Remove the thermostat from its backplate and gently check the ribbon cable between PCB and display for disconnection or obvious damage.
- Power check: Verify that the thermostat is receiving the correct supply voltage at its terminals using a multimeter if you are competent.
- Replace unit: Display or PCB-level repairs are not user-serviceable; replace the thermostat if the display remains non-functional.
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Repair Difficulty
Medium
3/5
Required Part
Ariston Smart Thermostat (Complete Unit)
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