Ariston Smart Thermostats Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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101
Thermostat display shows error 101 and heating does not start even when there is a demand for heat.
No Communication With Boiler (OpenTherm/Bus Failure)
102
Error 102 on thermostat, intermittent loss of control over boiler; heating sometimes starts late or not at all.
Intermittent Bus Communication / Signal Noise
103
Thermostat shows error 103 and cannot detect any heating zones or boiler type during setup.
Boiler Type Auto-Detection Failure
104
Error 104 displayed; thermostat reports that the boiler is in lockout and cannot start heating.
Boiler Lockout Detected by Thermostat
105
Thermostat shows error 105 and cannot control domestic hot water temperature from the app or screen.
DHW Control Channel Failure
106
Error 106 on thermostat; room temperature reading is clearly wrong (e.g. shows 5°C or 40°C indoors).
Internal Room Temperature Sensor Failure
107
Thermostat displays error 107 and cannot detect any external room sensor or floor sensor connected.
External Sensor Detection Failure
108
Error 108 appears; thermostat reports that the floor temperature is too high and heating is disabled.
Floor Overtemperature Protection Triggered
109
Thermostat shows error 109 and cannot control any heating zones; zone valves or actuators do not respond.
Zone Output Module Communication Failure
110
Error 110; thermostat cannot detect any wireless remote sensors or wireless room units.
Wireless Sensor Pairing Failure
111
Thermostat shows error 111 and reports low battery on wireless sensor or remote unit.
Low Battery in Wireless Accessory
112
Error 112; thermostat cannot connect to the home Wi‑Fi network and remote control via app is unavailable.
Wi‑Fi Connection Failure
113
Thermostat displays error 113 and cannot reach the Ariston cloud; app shows device offline even though Wi‑Fi is connected.
Cloud Server / Internet Connectivity Error
114
Error 114; thermostat time and schedules keep resetting or are incorrect after power cuts.
Real-Time Clock / Backup Power Failure
115
Thermostat shows error 115 and the display is very dim or completely blank, though the boiler still runs on its own controls.
Display Backlight / LCD Power Failure
116
Error 116; thermostat reports internal overtemperature and shuts down its outputs.
Thermostat Internal Overheat Protection
117
Thermostat shows error 117 and reports that the relay output is stuck or not responding.
Stuck Heating Relay / Output Failure
118
Error 118; thermostat cannot detect any power on its supply terminals.
No Power to Thermostat
119
Thermostat displays error 119 and cannot save new schedules or settings; changes are lost after reboot.
Non-Volatile Memory (NVM) Write Failure
120
Error 120; thermostat reports that the humidity sensor is faulty or readings are out of range.
Internal Humidity Sensor Failure
Symptom
Heating runs continuously even when the thermostat is set to OFF or a low temperature.
Heating Stuck On (Relay Welded or Wiring Bypass)
Symptom
Room temperature overshoots the setpoint by several degrees before the heating turns off.
Poor Temperature Control / Overshoot
Symptom
Thermostat app shows incorrect room names or duplicates, and control of rooms is confusing.
Configuration / Naming Conflict in Smart System
Symptom
Thermostat calls for heat but boiler does not start; no error code shown on thermostat or boiler.
No Heat Demand Transfer (Relay/Bus Not Activating Boiler)
Symptom
Thermostat does not control domestic hot water recirculation pump or cylinder as expected, even though configured.
DHW Control Misconfiguration
Symptom
Thermostat does not detect or control individual zones correctly in a multi-zone Ariston system.
Zone Mapping / Addressing Fault
Symptom
Thermostat does not follow programmed schedule; heating turns on and off at unexpected times.
Scheduling / Programming Fault
Symptom
Thermostat emits a buzzing or clicking noise frequently when controlling heating.
Noisy Relay Operation / Electrical Noise
Symptom
Thermostat fails to detect open windows or does not activate energy-saving features when windows are opened.
Open-Window Detection / Sensor Integration Failure
Symptom
Thermostat frequently disconnects from Wi‑Fi and shows offline in the app, then reconnects later.
Intermittent Wi‑Fi Connectivity
Symptom
Thermostat frequently loses pairing with wireless boiler receiver or gateway, causing intermittent heating control.
Unstable RF Link Between Thermostat and Receiver
Symptom
Thermostat or its backplate feels unusually hot to the touch during normal operation.
Overheating of Electronics or Backplate
Symptom
Thermostat or its wiring emits a burning smell or shows signs of scorching.
Overheating / Electrical Damage
Symptom
Thermostat screen is frozen and does not respond to touch or button presses.
User Interface Lockup / Firmware Hang
Symptom
Thermostat shows large temperature swings and the boiler short-cycles (frequent on/off).
Short Cycling / Poor Boiler-Thermostat Matching
Symptom
Underfloor heating controlled by the thermostat is slow to warm up and rooms never reach the set temperature.
Insufficient Underfloor Heating Output / Control Mismatch
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 101 |
Thermostat display shows error 101 and heating does not start even when there is a demand for heat.
|
No Communication With Boiler (OpenTherm/Bus Failure) | View Details |
| 102 |
Error 102 on thermostat, intermittent loss of control over boiler; heating sometimes starts late or not at all.
|
Intermittent Bus Communication / Signal Noise | View Details |
| 103 |
Thermostat shows error 103 and cannot detect any heating zones or boiler type during setup.
|
Boiler Type Auto-Detection Failure | View Details |
| 104 |
Error 104 displayed; thermostat reports that the boiler is in lockout and cannot start heating.
|
Boiler Lockout Detected by Thermostat | View Details |
| 105 |
Thermostat shows error 105 and cannot control domestic hot water temperature from the app or screen.
|
DHW Control Channel Failure | View Details |
| 106 |
Error 106 on thermostat; room temperature reading is clearly wrong (e.g. shows 5°C or 40°C indoors).
|
Internal Room Temperature Sensor Failure | View Details |
| 107 |
Thermostat displays error 107 and cannot detect any external room sensor or floor sensor connected.
|
External Sensor Detection Failure | View Details |
| 108 |
Error 108 appears; thermostat reports that the floor temperature is too high and heating is disabled.
|
Floor Overtemperature Protection Triggered | View Details |
| 109 |
Thermostat shows error 109 and cannot control any heating zones; zone valves or actuators do not respond.
|
Zone Output Module Communication Failure | View Details |
| 110 |
Error 110; thermostat cannot detect any wireless remote sensors or wireless room units.
|
Wireless Sensor Pairing Failure | View Details |
| 111 |
Thermostat shows error 111 and reports low battery on wireless sensor or remote unit.
|
Low Battery in Wireless Accessory | View Details |
| 112 |
Error 112; thermostat cannot connect to the home Wi‑Fi network and remote control via app is unavailable.
|
Wi‑Fi Connection Failure | View Details |
| 113 |
Thermostat displays error 113 and cannot reach the Ariston cloud; app shows device offline even though Wi‑Fi is connected.
|
Cloud Server / Internet Connectivity Error | View Details |
| 114 |
Error 114; thermostat time and schedules keep resetting or are incorrect after power cuts.
|
Real-Time Clock / Backup Power Failure | View Details |
| 115 |
Thermostat shows error 115 and the display is very dim or completely blank, though the boiler still runs on its own controls.
|
Display Backlight / LCD Power Failure | View Details |
| 116 |
Error 116; thermostat reports internal overtemperature and shuts down its outputs.
|
Thermostat Internal Overheat Protection | View Details |
| 117 |
Thermostat shows error 117 and reports that the relay output is stuck or not responding.
|
Stuck Heating Relay / Output Failure | View Details |
| 118 |
Error 118; thermostat cannot detect any power on its supply terminals.
|
No Power to Thermostat | View Details |
| 119 |
Thermostat displays error 119 and cannot save new schedules or settings; changes are lost after reboot.
|
Non-Volatile Memory (NVM) Write Failure | View Details |
| 120 |
Error 120; thermostat reports that the humidity sensor is faulty or readings are out of range.
|
Internal Humidity Sensor Failure | View Details |
| – |
Heating runs continuously even when the thermostat is set to OFF or a low temperature.
|
Heating Stuck On (Relay Welded or Wiring Bypass) | View Details |
| – |
Room temperature overshoots the setpoint by several degrees before the heating turns off.
|
Poor Temperature Control / Overshoot | View Details |
| – |
Thermostat app shows incorrect room names or duplicates, and control of rooms is confusing.
|
Configuration / Naming Conflict in Smart System | View Details |
| – |
Thermostat calls for heat but boiler does not start; no error code shown on thermostat or boiler.
|
No Heat Demand Transfer (Relay/Bus Not Activating Boiler) | View Details |
| – |
Thermostat does not control domestic hot water recirculation pump or cylinder as expected, even though configured.
|
DHW Control Misconfiguration | View Details |
| – |
Thermostat does not detect or control individual zones correctly in a multi-zone Ariston system.
|
Zone Mapping / Addressing Fault | View Details |
| – |
Thermostat does not follow programmed schedule; heating turns on and off at unexpected times.
|
Scheduling / Programming Fault | View Details |
| – |
Thermostat emits a buzzing or clicking noise frequently when controlling heating.
|
Noisy Relay Operation / Electrical Noise | View Details |
| – |
Thermostat fails to detect open windows or does not activate energy-saving features when windows are opened.
|
Open-Window Detection / Sensor Integration Failure | View Details |
| – |
Thermostat frequently disconnects from Wi‑Fi and shows offline in the app, then reconnects later.
|
Intermittent Wi‑Fi Connectivity | View Details |
| – |
Thermostat frequently loses pairing with wireless boiler receiver or gateway, causing intermittent heating control.
|
Unstable RF Link Between Thermostat and Receiver | View Details |
| – |
Thermostat or its backplate feels unusually hot to the touch during normal operation.
|
Overheating of Electronics or Backplate | View Details |
| – |
Thermostat or its wiring emits a burning smell or shows signs of scorching.
|
Overheating / Electrical Damage | View Details |
| – |
Thermostat screen is frozen and does not respond to touch or button presses.
|
User Interface Lockup / Firmware Hang | View Details |
| – |
Thermostat shows large temperature swings and the boiler short-cycles (frequent on/off).
|
Short Cycling / Poor Boiler-Thermostat Matching | View Details |
| – |
Underfloor heating controlled by the thermostat is slow to warm up and rooms never reach the set temperature.
|
Insufficient Underfloor Heating Output / Control Mismatch | View Details |
No matching codes found
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