Ariston Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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101
Boiler locks out with code 101, no heating or hot water, red fault LED on
Primary Circuit Overheat Lockout
102
Boiler displays 102 and locks out, no heating or hot water
Water Pressure Sensor Fault
103
Boiler shows 103, frequent lockouts, radiators only warm at top or not heating fully
Primary Circuit Circulation Fault / Overtemperature
104
Boiler displays 104, shuts down shortly after starting, flow temperature rises very quickly
Flow Temperature Rise Too Fast / Flow Sensor Overheat
105
Boiler shows 105, frequent overheat lockouts, loud kettling noises from boiler
Primary Circuit Overheat / Kettling
106
Boiler displays 106, intermittent lockouts, sometimes works after reset
Flow Temperature Sensor Fault
107
Boiler shows 107, no heating or hot water, pressure gauge may read low
Low Water Pressure Lockout
108
Boiler displays 108, no operation, pressure gauge at zero or very low
No Water Pressure / System Empty
109
Boiler shows 109, pressure rises quickly when heating, water discharges from safety valve
High System Pressure / Overpressure
110
Boiler displays 110, very hot casing, no heating or hot water
Safety Thermostat Tripped / Overheat Lockout
111
Boiler shows 111, will not fire, fan may not start
Flue Overheat / Flue Thermostat Trip
112
Boiler displays 112, intermittent operation, sometimes shuts down during long runs
Return Temperature Sensor Fault
201
Boiler shows 201, no ignition, fan may run briefly then stop
Ignition Failure / No Flame Detected
202
Boiler displays 202, attempts to ignite but locks out, sometimes lights then goes out
Flame Detection Fault
203
Boiler shows 203, fan runs but no ignition, or stops unexpectedly
Fan / Air Pressure Switch Fault
301
Boiler displays 301, no response to controls, some LEDs may flash
User Interface / Control Panel Communication Fault
302
Boiler shows 302, random resets, display flickers, sometimes loses settings
Main PCB Power Supply / Low Voltage Fault
303
Boiler displays 303, external controls (room thermostat, timer) not recognised
External Control / Bus Communication Fault
304
Boiler shows 304, hot water works but heating does not respond to thermostat
CH Demand Signal Fault
501
Boiler displays 501, ignition lockout, red LED on, no flame
Ignition Lockout (No Flame)
601
Boiler shows 601, fan runs continuously or not at all, no ignition
Fan Speed / Tachometer Fault
602
Boiler displays 602, intermittent fan-related lockouts, sometimes works after reset
Air Pressure Switch / Differential Pressure Fault
701
Boiler shows 701, DHW temperature unstable or too hot, CH may be normal
DHW Temperature Sensor Fault
702
Boiler displays 702, hot water demand not recognised, no burner ignition when tap opened
DHW Flow Sensor / Turbine Fault
703
Boiler shows 703, DHW temperature fluctuates, burner cycles rapidly during hot water use
DHW Modulation / Flow Regulation Fault
801
Boiler displays 801, communication error with external Ariston Net / Cube thermostat
OpenTherm / Bus Communication Error
Symptom
Boiler casing vibrates or rattles loudly during operation
Mechanical Vibration / Loose Components
Symptom
Boiler condensate pipe dripping heavily or gurgling noises from boiler
Condensate Drainage Issue
Symptom
Boiler emits a burning smell or plastic smell during operation
Overheating Electrical Component or Dust Burn-Off
Symptom
Boiler fan runs but burner does not light, no error code shown
Intermittent Ignition / Control Fault
Symptom
Boiler frequently loses pressure and needs topping up
Chronic Pressure Loss
Symptom
Boiler leaking water from underneath the casing or pipe connections
Internal Water Leak
Symptom
Boiler makes a high-pitched whine or grinding noise during operation
Pump or Fan Mechanical Wear
Symptom
Boiler makes loud banging or knocking noises when starting or stopping
Water Hammer / Expansion Noise
Symptom
Boiler operates but makes a constant trickling or running water noise
Air in System / Bypass Flow Noise
Symptom
Boiler repeatedly starts and stops (short cycling) without reaching set temperature
Short Cycling / Oversized Boiler or Control Issue
Symptom
Boiler runs but radiators are only warm at the top and cold at the bottom
Sludge Build-Up in Radiators
Symptom
Boiler runs for heating but hot water is lukewarm or cold
DHW Priority / Diverter Valve Fault
Symptom
Boiler will not start at all, no lights or display
No Power / Electrical Supply Fault
Symptom
Hot water temperature fluctuates between hot and cold during shower use
DHW Temperature Instability
Symptom
Radiators not heating properly while hot water works fine
Central Heating Circuit Flow Problem
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 101 |
Boiler locks out with code 101, no heating or hot water, red fault LED on
|
Primary Circuit Overheat Lockout | View Details |
| 102 |
Boiler displays 102 and locks out, no heating or hot water
|
Water Pressure Sensor Fault | View Details |
| 103 |
Boiler shows 103, frequent lockouts, radiators only warm at top or not heating fully
|
Primary Circuit Circulation Fault / Overtemperature | View Details |
| 104 |
Boiler displays 104, shuts down shortly after starting, flow temperature rises very quickly
|
Flow Temperature Rise Too Fast / Flow Sensor Overheat | View Details |
| 105 |
Boiler shows 105, frequent overheat lockouts, loud kettling noises from boiler
|
Primary Circuit Overheat / Kettling | View Details |
| 106 |
Boiler displays 106, intermittent lockouts, sometimes works after reset
|
Flow Temperature Sensor Fault | View Details |
| 107 |
Boiler shows 107, no heating or hot water, pressure gauge may read low
|
Low Water Pressure Lockout | View Details |
| 108 |
Boiler displays 108, no operation, pressure gauge at zero or very low
|
No Water Pressure / System Empty | View Details |
| 109 |
Boiler shows 109, pressure rises quickly when heating, water discharges from safety valve
|
High System Pressure / Overpressure | View Details |
| 110 |
Boiler displays 110, very hot casing, no heating or hot water
|
Safety Thermostat Tripped / Overheat Lockout | View Details |
| 111 |
Boiler shows 111, will not fire, fan may not start
|
Flue Overheat / Flue Thermostat Trip | View Details |
| 112 |
Boiler displays 112, intermittent operation, sometimes shuts down during long runs
|
Return Temperature Sensor Fault | View Details |
| 201 |
Boiler shows 201, no ignition, fan may run briefly then stop
|
Ignition Failure / No Flame Detected | View Details |
| 202 |
Boiler displays 202, attempts to ignite but locks out, sometimes lights then goes out
|
Flame Detection Fault | View Details |
| 203 |
Boiler shows 203, fan runs but no ignition, or stops unexpectedly
|
Fan / Air Pressure Switch Fault | View Details |
| 301 |
Boiler displays 301, no response to controls, some LEDs may flash
|
User Interface / Control Panel Communication Fault | View Details |
| 302 |
Boiler shows 302, random resets, display flickers, sometimes loses settings
|
Main PCB Power Supply / Low Voltage Fault | View Details |
| 303 |
Boiler displays 303, external controls (room thermostat, timer) not recognised
|
External Control / Bus Communication Fault | View Details |
| 304 |
Boiler shows 304, hot water works but heating does not respond to thermostat
|
CH Demand Signal Fault | View Details |
| 501 |
Boiler displays 501, ignition lockout, red LED on, no flame
|
Ignition Lockout (No Flame) | View Details |
| 601 |
Boiler shows 601, fan runs continuously or not at all, no ignition
|
Fan Speed / Tachometer Fault | View Details |
| 602 |
Boiler displays 602, intermittent fan-related lockouts, sometimes works after reset
|
Air Pressure Switch / Differential Pressure Fault | View Details |
| 701 |
Boiler shows 701, DHW temperature unstable or too hot, CH may be normal
|
DHW Temperature Sensor Fault | View Details |
| 702 |
Boiler displays 702, hot water demand not recognised, no burner ignition when tap opened
|
DHW Flow Sensor / Turbine Fault | View Details |
| 703 |
Boiler shows 703, DHW temperature fluctuates, burner cycles rapidly during hot water use
|
DHW Modulation / Flow Regulation Fault | View Details |
| 801 |
Boiler displays 801, communication error with external Ariston Net / Cube thermostat
|
OpenTherm / Bus Communication Error | View Details |
| – |
Boiler casing vibrates or rattles loudly during operation
|
Mechanical Vibration / Loose Components | View Details |
| – |
Boiler condensate pipe dripping heavily or gurgling noises from boiler
|
Condensate Drainage Issue | View Details |
| – |
Boiler emits a burning smell or plastic smell during operation
|
Overheating Electrical Component or Dust Burn-Off | View Details |
| – |
Boiler fan runs but burner does not light, no error code shown
|
Intermittent Ignition / Control Fault | View Details |
| – |
Boiler frequently loses pressure and needs topping up
|
Chronic Pressure Loss | View Details |
| – |
Boiler leaking water from underneath the casing or pipe connections
|
Internal Water Leak | View Details |
| – |
Boiler makes a high-pitched whine or grinding noise during operation
|
Pump or Fan Mechanical Wear | View Details |
| – |
Boiler makes loud banging or knocking noises when starting or stopping
|
Water Hammer / Expansion Noise | View Details |
| – |
Boiler operates but makes a constant trickling or running water noise
|
Air in System / Bypass Flow Noise | View Details |
| – |
Boiler repeatedly starts and stops (short cycling) without reaching set temperature
|
Short Cycling / Oversized Boiler or Control Issue | View Details |
| – |
Boiler runs but radiators are only warm at the top and cold at the bottom
|
Sludge Build-Up in Radiators | View Details |
| – |
Boiler runs for heating but hot water is lukewarm or cold
|
DHW Priority / Diverter Valve Fault | View Details |
| – |
Boiler will not start at all, no lights or display
|
No Power / Electrical Supply Fault | View Details |
| – |
Hot water temperature fluctuates between hot and cold during shower use
|
DHW Temperature Instability | View Details |
| – |
Radiators not heating properly while hot water works fine
|
Central Heating Circuit Flow Problem | View Details |
No matching codes found
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