Sime
Sime Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E01
Boiler does not ignite, display shows E01, no flame symbol, heating and hot water unavailable
Ignition Failure / Flame Not Detected
E02
Boiler locks out with E02, overheats then shuts down, may make kettling noises before stopping
Primary Circuit Overheat / Safety Thermostat Trip
E03
Boiler shows E03 and will not start, fan may run briefly then stop
Flue Gas Safety / Flue Thermostat Trip (Overheat in Flue Path)
E04
Boiler displays E04, pressure gauge at zero or very low, boiler will not fire
Low Water Pressure / Insufficient System Charge
E05
Boiler shows E05, heating does not start, flow temperature reading is abnormal or fixed
Flow Temperature Sensor (NTC) Fault
E06
Boiler displays E06, hot water temperature fluctuates or is incorrect, heating may still work.
DHW Temperature Sensor (NTC) Fault
E07
Boiler shows E07, fan may not start, ignition sequence does not begin.
Fan / Air Pressure Switch Fault
E08
Boiler displays E08, no heating or hot water, pump may not run.
Circulation Pump Fault / Pump Feedback Error
E09
Boiler shows E09, burner stops unexpectedly, may relate to gas valve control.
Gas Valve Control / Modulation Fault
E10
Boiler displays E10, no heating or hot water, may be associated with the return temperature sensor.
Return Temperature Sensor (NTC) Fault
E11
Boiler shows E11; ignition may start but lockout occurs, sometimes associated with an ionisation fault.
Flame Detection / Ionisation Fault
E12
Boiler displays E12, which may indicate a communication or internal electronics fault, making the boiler unresponsive.
Main PCB / Control Board Fault
E13
Boiler shows E13, often related to flue or condensate issues, causing the boiler to lock out.
Flue System / Condensate Drain Fault
E14
Boiler displays E14, which may be associated with the fan speed or flue gas sensor on some Sime models.
Fan Speed / Combustion Control Fault
E15
Boiler shows E15, which may indicate a domestic hot water flow sensor or turbine fault on combi models.
DHW Flow Detection Fault
E16
Boiler displays E16, which may be related to the flue gas temperature sensor on some Sime condensing models.
Flue Gas Temperature Sensor Fault
E17
Boiler displays E17, which may indicate an ionization current out of range or an unstable flame.
Unstable Combustion / Flame Signal Out of Range
E18
Boiler displays E18, often associated with low system water content or a low flow rate.
Insufficient Water Flow / Flow Switch Fault
E19
Boiler displays E19, which may indicate a parameter or configuration error after PCB replacement.
Configuration / Parameter Fault
E20
Boiler displays E20, which may indicate an external control or thermostat fault.
External Control / Room Thermostat Fault
Symptom
Boiler cycles on and off rapidly when only a small radiator or towel rail is open.
Low System Load / Bypass or Oversizing Issue
Symptom
Boiler display works, but buttons or selector knobs do not respond.
User Interface / Control Panel Fault
Symptom
Boiler emits a strong smell of gas or combustion fumes.
Gas Leak / Flue Gas Escape
Symptom
Boiler frequently locks out and needs manual resetting, with varying or no error codes.
Intermittent Lockout
Symptom
Boiler frequently loses pressure and needs topping up every few days.
Chronic Pressure Loss
Symptom
Boiler heats radiators even when the room thermostat is turned down or off.
Uncontrolled Heating / Valve Stuck Open
Symptom
Boiler is leaking water from underneath the casing or pipe connections.
Internal Water Leak
Symptom
Boiler makes loud banging or 'kettling' noises during operation, especially when heating.
Kettling / Localised Boiling in Heat Exchanger
Symptom
Boiler provides heating but no domestic hot water on a combi system.
No DHW Production on Combi Boiler
Symptom
Boiler provides hot water but no central heating on a combi or system boiler.
No Central Heating Output
Symptom
Boiler runs but makes a loud humming or vibrating noise through the house.
Mechanical Vibration / Resonance
Symptom
Boiler starts, then shuts down after a few seconds without showing an error code.
Short Cycling / Early Flame Loss
Symptom
Boiler trips the electrical circuit breaker or RCD when it starts.
Electrical Short or Earth Leakage
Symptom
Boiler will not start at all; no lights or display.
No Power / Dead Boiler
Symptom
Hot water temperature fluctuates between hot and cold during shower use.
Inconsistent DHW Temperature Control
Symptom
Radiators do not get hot even though the boiler appears to be running.
Poor Central Heating Circulation
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Boiler does not ignite, display shows E01, no flame symbol, heating and hot water unavailable
|
Ignition Failure / Flame Not Detected | View Details |
| E02 |
Boiler locks out with E02, overheats then shuts down, may make kettling noises before stopping
|
Primary Circuit Overheat / Safety Thermostat Trip | View Details |
| E03 |
Boiler shows E03 and will not start, fan may run briefly then stop
|
Flue Gas Safety / Flue Thermostat Trip (Overheat in Flue Path) | View Details |
| E04 |
Boiler displays E04, pressure gauge at zero or very low, boiler will not fire
|
Low Water Pressure / Insufficient System Charge | View Details |
| E05 |
Boiler shows E05, heating does not start, flow temperature reading is abnormal or fixed
|
Flow Temperature Sensor (NTC) Fault | View Details |
| E06 |
Boiler displays E06, hot water temperature fluctuates or is incorrect, heating may still work.
|
DHW Temperature Sensor (NTC) Fault | View Details |
| E07 |
Boiler shows E07, fan may not start, ignition sequence does not begin.
|
Fan / Air Pressure Switch Fault | View Details |
| E08 |
Boiler displays E08, no heating or hot water, pump may not run.
|
Circulation Pump Fault / Pump Feedback Error | View Details |
| E09 |
Boiler shows E09, burner stops unexpectedly, may relate to gas valve control.
|
Gas Valve Control / Modulation Fault | View Details |
| E10 |
Boiler displays E10, no heating or hot water, may be associated with the return temperature sensor.
|
Return Temperature Sensor (NTC) Fault | View Details |
| E11 |
Boiler shows E11; ignition may start but lockout occurs, sometimes associated with an ionisation fault.
|
Flame Detection / Ionisation Fault | View Details |
| E12 |
Boiler displays E12, which may indicate a communication or internal electronics fault, making the boiler unresponsive.
|
Main PCB / Control Board Fault | View Details |
| E13 |
Boiler shows E13, often related to flue or condensate issues, causing the boiler to lock out.
|
Flue System / Condensate Drain Fault | View Details |
| E14 |
Boiler displays E14, which may be associated with the fan speed or flue gas sensor on some Sime models.
|
Fan Speed / Combustion Control Fault | View Details |
| E15 |
Boiler shows E15, which may indicate a domestic hot water flow sensor or turbine fault on combi models.
|
DHW Flow Detection Fault | View Details |
| E16 |
Boiler displays E16, which may be related to the flue gas temperature sensor on some Sime condensing models.
|
Flue Gas Temperature Sensor Fault | View Details |
| E17 |
Boiler displays E17, which may indicate an ionization current out of range or an unstable flame.
|
Unstable Combustion / Flame Signal Out of Range | View Details |
| E18 |
Boiler displays E18, often associated with low system water content or a low flow rate.
|
Insufficient Water Flow / Flow Switch Fault | View Details |
| E19 |
Boiler displays E19, which may indicate a parameter or configuration error after PCB replacement.
|
Configuration / Parameter Fault | View Details |
| E20 |
Boiler displays E20, which may indicate an external control or thermostat fault.
|
External Control / Room Thermostat Fault | View Details |
| – |
Boiler cycles on and off rapidly when only a small radiator or towel rail is open.
|
Low System Load / Bypass or Oversizing Issue | View Details |
| – |
Boiler display works, but buttons or selector knobs do not respond.
|
User Interface / Control Panel Fault | View Details |
| – |
Boiler emits a strong smell of gas or combustion fumes.
|
Gas Leak / Flue Gas Escape | View Details |
| – |
Boiler frequently locks out and needs manual resetting, with varying or no error codes.
|
Intermittent Lockout | View Details |
| – |
Boiler frequently loses pressure and needs topping up every few days.
|
Chronic Pressure Loss | View Details |
| – |
Boiler heats radiators even when the room thermostat is turned down or off.
|
Uncontrolled Heating / Valve Stuck Open | View Details |
| – |
Boiler is leaking water from underneath the casing or pipe connections.
|
Internal Water Leak | View Details |
| – |
Boiler makes loud banging or 'kettling' noises during operation, especially when heating.
|
Kettling / Localised Boiling in Heat Exchanger | View Details |
| – |
Boiler provides heating but no domestic hot water on a combi system.
|
No DHW Production on Combi Boiler | View Details |
| – |
Boiler provides hot water but no central heating on a combi or system boiler.
|
No Central Heating Output | View Details |
| – |
Boiler runs but makes a loud humming or vibrating noise through the house.
|
Mechanical Vibration / Resonance | View Details |
| – |
Boiler starts, then shuts down after a few seconds without showing an error code.
|
Short Cycling / Early Flame Loss | View Details |
| – |
Boiler trips the electrical circuit breaker or RCD when it starts.
|
Electrical Short or Earth Leakage | View Details |
| – |
Boiler will not start at all; no lights or display.
|
No Power / Dead Boiler | View Details |
| – |
Hot water temperature fluctuates between hot and cold during shower use.
|
Inconsistent DHW Temperature Control | View Details |
| – |
Radiators do not get hot even though the boiler appears to be running.
|
Poor Central Heating Circulation | View Details |
No matching codes found
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