Ideal
Ideal Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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C0
Ideal boiler displays C0, boiler may appear to run pump without firing
Pump Overrun / Anti-Seize Cycle
C2
Ideal boiler shows C2 and may not respond to thermostat commands
Communication With Room Thermostat / Control Fault
C4
Ideal boiler displays C4 and may not fire for central heating
Flow Temperature Sensor Out of Range (CH)
C6
Ideal boiler shows C6 and may not modulate correctly
Fan Speed / Air Pressure Sensing Issue
C7
Ideal boiler displays C7 and may not fire
Low System Water Content / Flow Issue
C8
Ideal boiler shows C8 and may cycle or limit output
Return Temperature Sensor Out of Range
C9
Ideal boiler displays C9 and may not provide stable hot water
DHW Temperature Sensor Out of Range
F1
Ideal boiler displays F1 and will not fire, no heating or hot water
Low System Water Pressure Lockout
F2
Ideal boiler shows F2 and shuts down during operation
Flame Loss During Operation
F3
Ideal boiler displays F3 and will not start, fan can be heard or may not run
Fan Speed or Fan Fault
F4
Ideal boiler shows F4 and fails to ignite, no flame established
Ignition Failure
F5
Ideal boiler displays F5 and locks out, often accompanied by loud ignition or poor burning
Flame Detection Fault / Flame Signal Error
F7
Ideal boiler shows F7 and will not fire, often after power interruption
Low Mains Voltage / PCB Supply Fault
F9
Ideal boiler displays F9 and shuts down, may occur intermittently
PCB Fault / Internal Error
H0
Ideal boiler displays H0, boiler may still operate but with limited output
Service Reminder / Maintenance Indicator
H1
Ideal boiler shows H1 and may reduce output or cycle frequently
Flow Temperature Control / High Temperature Operation
H2
Ideal boiler displays H2 and may shut down intermittently
Flow Thermistor / Temperature Sensor Fault
H3
Ideal boiler shows H3, hot water temperature unstable or boiler cycles rapidly
Return Thermistor / Temperature Sensor Fault
H4
Ideal boiler displays H4, often with poor hot water performance
Domestic Hot Water (DHW) Thermistor Fault
H5
Ideal boiler shows H5 and may shut down on high temperature
Flow Temperature Differential / Overheat Control
H6
Ideal boiler displays H6, hot water temperature may be erratic
DHW Flow Sensor / Turbine Fault
H7
Ideal boiler shows H7 and may not respond correctly to thermostat
Communication Fault With External Controls
H8
Ideal boiler displays H8 and may limit output or cycle
Flow/Return Temperature Differential Too High
H9
Ideal boiler shows H9 and may shut down on overheat
Overheat Thermostat / Safety Cut-out Operation
L1
Ideal boiler shows L1 and locks out, often with no hot water or heating
Ignition Lockout (Repeated Ignition Failure)
L2
Ideal boiler displays L2 and will not fire, often after a failed ignition attempt
Flame Loss / Flame Lockout
L5
Ideal boiler shows L5 after power interruption or lockout, boiler unresponsive until reset
Lockout Due to False Flame / Power Interruption
L6
Ideal boiler displays L6 and will not operate
False Flame Detection / Flame On Signal With No Demand
L9
Ideal boiler shows L9 and may intermittently stop and start
PCB Communication / Internal Lockout
Symptom
Boiler display completely dead, no lights or response
No Power to Boiler
Symptom
Boiler does not respond to room thermostat or programmer, stays off
Control Signal Failure
Symptom
Boiler frequently loses pressure and needs topping up every few days
Chronic Pressure Loss
Symptom
Boiler leaking water from underneath the case or pipe connections
Internal Water Leak
Symptom
Boiler makes loud banging or kettling noises when heating is on
Kettling Due to Scale or Sludge in Heat Exchanger
Symptom
Boiler or flue emits unusual smells (metallic, burning, or fume-like)
Combustion or Electrical Overheating Issue
Symptom
Boiler runs but radiators only get warm at the bottom or some stay cold
Poor Circulation / Sludge in System
Symptom
Boiler short cycles (frequently turns on and off) and rooms do not reach temperature
Short Cycling Due to Oversizing or Control Issues
Symptom
Boiler trips the electrical circuit breaker or RCD when it tries to start
Electrical Short or Earth Leakage
Symptom
Boiler very noisy fan or whistling noise from flue during operation
Fan or Flue Resonance / Airflow Issue
Symptom
Condensate pipe dripping heavily or gurgling noises from boiler
Condensate Drainage Issue
Symptom
No heating but hot water works correctly on an Ideal combi boiler
Central Heating Demand or Diverter Valve Fault
Symptom
No hot water but heating works on an Ideal combi boiler
DHW Flow or Diverter Valve Fault
Symptom
Radiators get hot when only hot water is demanded on a combi boiler
Diverter Valve Passing / Cross-Flow
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| C0 |
Ideal boiler displays C0, boiler may appear to run pump without firing
|
Pump Overrun / Anti-Seize Cycle | View Details |
| C2 |
Ideal boiler shows C2 and may not respond to thermostat commands
|
Communication With Room Thermostat / Control Fault | View Details |
| C4 |
Ideal boiler displays C4 and may not fire for central heating
|
Flow Temperature Sensor Out of Range (CH) | View Details |
| C6 |
Ideal boiler shows C6 and may not modulate correctly
|
Fan Speed / Air Pressure Sensing Issue | View Details |
| C7 |
Ideal boiler displays C7 and may not fire
|
Low System Water Content / Flow Issue | View Details |
| C8 |
Ideal boiler shows C8 and may cycle or limit output
|
Return Temperature Sensor Out of Range | View Details |
| C9 |
Ideal boiler displays C9 and may not provide stable hot water
|
DHW Temperature Sensor Out of Range | View Details |
| F1 |
Ideal boiler displays F1 and will not fire, no heating or hot water
|
Low System Water Pressure Lockout | View Details |
| F2 |
Ideal boiler shows F2 and shuts down during operation
|
Flame Loss During Operation | View Details |
| F3 |
Ideal boiler displays F3 and will not start, fan can be heard or may not run
|
Fan Speed or Fan Fault | View Details |
| F4 |
Ideal boiler shows F4 and fails to ignite, no flame established
|
Ignition Failure | View Details |
| F5 |
Ideal boiler displays F5 and locks out, often accompanied by loud ignition or poor burning
|
Flame Detection Fault / Flame Signal Error | View Details |
| F7 |
Ideal boiler shows F7 and will not fire, often after power interruption
|
Low Mains Voltage / PCB Supply Fault | View Details |
| F9 |
Ideal boiler displays F9 and shuts down, may occur intermittently
|
PCB Fault / Internal Error | View Details |
| H0 |
Ideal boiler displays H0, boiler may still operate but with limited output
|
Service Reminder / Maintenance Indicator | View Details |
| H1 |
Ideal boiler shows H1 and may reduce output or cycle frequently
|
Flow Temperature Control / High Temperature Operation | View Details |
| H2 |
Ideal boiler displays H2 and may shut down intermittently
|
Flow Thermistor / Temperature Sensor Fault | View Details |
| H3 |
Ideal boiler shows H3, hot water temperature unstable or boiler cycles rapidly
|
Return Thermistor / Temperature Sensor Fault | View Details |
| H4 |
Ideal boiler displays H4, often with poor hot water performance
|
Domestic Hot Water (DHW) Thermistor Fault | View Details |
| H5 |
Ideal boiler shows H5 and may shut down on high temperature
|
Flow Temperature Differential / Overheat Control | View Details |
| H6 |
Ideal boiler displays H6, hot water temperature may be erratic
|
DHW Flow Sensor / Turbine Fault | View Details |
| H7 |
Ideal boiler shows H7 and may not respond correctly to thermostat
|
Communication Fault With External Controls | View Details |
| H8 |
Ideal boiler displays H8 and may limit output or cycle
|
Flow/Return Temperature Differential Too High | View Details |
| H9 |
Ideal boiler shows H9 and may shut down on overheat
|
Overheat Thermostat / Safety Cut-out Operation | View Details |
| L1 |
Ideal boiler shows L1 and locks out, often with no hot water or heating
|
Ignition Lockout (Repeated Ignition Failure) | View Details |
| L2 |
Ideal boiler displays L2 and will not fire, often after a failed ignition attempt
|
Flame Loss / Flame Lockout | View Details |
| L5 |
Ideal boiler shows L5 after power interruption or lockout, boiler unresponsive until reset
|
Lockout Due to False Flame / Power Interruption | View Details |
| L6 |
Ideal boiler displays L6 and will not operate
|
False Flame Detection / Flame On Signal With No Demand | View Details |
| L9 |
Ideal boiler shows L9 and may intermittently stop and start
|
PCB Communication / Internal Lockout | View Details |
| – |
Boiler display completely dead, no lights or response
|
No Power to Boiler | View Details |
| – |
Boiler does not respond to room thermostat or programmer, stays off
|
Control Signal Failure | View Details |
| – |
Boiler frequently loses pressure and needs topping up every few days
|
Chronic Pressure Loss | View Details |
| – |
Boiler leaking water from underneath the case or pipe connections
|
Internal Water Leak | View Details |
| – |
Boiler makes loud banging or kettling noises when heating is on
|
Kettling Due to Scale or Sludge in Heat Exchanger | View Details |
| – |
Boiler or flue emits unusual smells (metallic, burning, or fume-like)
|
Combustion or Electrical Overheating Issue | View Details |
| – |
Boiler runs but radiators only get warm at the bottom or some stay cold
|
Poor Circulation / Sludge in System | View Details |
| – |
Boiler short cycles (frequently turns on and off) and rooms do not reach temperature
|
Short Cycling Due to Oversizing or Control Issues | View Details |
| – |
Boiler trips the electrical circuit breaker or RCD when it tries to start
|
Electrical Short or Earth Leakage | View Details |
| – |
Boiler very noisy fan or whistling noise from flue during operation
|
Fan or Flue Resonance / Airflow Issue | View Details |
| – |
Condensate pipe dripping heavily or gurgling noises from boiler
|
Condensate Drainage Issue | View Details |
| – |
No heating but hot water works correctly on an Ideal combi boiler
|
Central Heating Demand or Diverter Valve Fault | View Details |
| – |
No hot water but heating works on an Ideal combi boiler
|
DHW Flow or Diverter Valve Fault | View Details |
| – |
Radiators get hot when only hot water is demanded on a combi boiler
|
Diverter Valve Passing / Cross-Flow | View Details |
No matching codes found
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