Sime
Sime Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A01
Furnace attempts to ignite but fails; burner does not light and unit locks out after several tries.
Ignition Failure / No Flame Detection
A02
Furnace lights briefly then shuts down; flame appears but is lost within a few seconds and the unit locks out.
Flame Loss After Ignition
A03
Furnace shuts down and displays an overheat/limit error; casing may feel unusually hot and burner will not restart until cooled.
Overheat Thermostat Tripped
A04
Furnace does not start; display shows low water pressure or lockout related to system pressure.
Low System Water Pressure (Hydronic Sime Furnace/Boiler)
A05
Furnace locks out with a flue or exhaust fault; fan may run briefly then stop.
Flue Gas Exhaust / Fan Fault
A06
Furnace shows an ionization or flame signal error even though the burner appears to be lit.
Flame Signal Too Weak or Absent
A07
Furnace displays a fan speed or fan tachometer error; burner does not ignite.
Fan Speed Control / Tachometer Fault
A08
Furnace indicates a gas valve or modulation fault; burner may stay at minimum or not light at all.
Gas Valve Control / Modulation Error
A09
Furnace shows a return sensor or flow sensor error; unit may overheat or shut down prematurely.
Flow/Return Temperature Sensor Fault
A10
Furnace indicates a domestic hot water (DHW) sensor error on combi models; hot water may be unstable or unavailable.
DHW Temperature Sensor Fault
A11
Furnace displays a flow switch or flow sensor error; burner will not fire for heating or DHW.
Water Flow Detection Fault
A12
Furnace shows a flue temperature sensor error; unit may shut down shortly after ignition.
Flue Gas Temperature Sensor Fault
A13
Furnace indicates a condensate or drain fault; unit may shut down during operation, especially in cold weather.
Condensate Drain Blockage
A14
Furnace shows a communication error between the main control board and user interface or remote controller.
Control Board Communication Fault
A15
Furnace indicates a power supply or mains frequency error; unit may not start or may reset intermittently.
Mains Voltage / Frequency Fault
E01
Furnace displays E01 and will not ignite; often associated with ignition or flame detection problems.
General Ignition Lockout
E02
Furnace displays E02 and shuts down; often linked to overheat or safety thermostat activation.
Safety Thermostat / Overheat Lockout
E03
Furnace displays E03 and stops; often associated with flue or air pressure switch problems.
Air Pressure Switch / Flue Safety Fault
E04
Furnace displays E04; typically related to low water pressure or water circulation issues on hydronic models.
Low Water Pressure / Circulation Fault
E05
Furnace displays E05; often associated with flow temperature sensor issues.
Flow NTC Sensor Error
E06
Furnace displays E06; typically related to return temperature sensor problems.
Return NTC Sensor Error
E07
Furnace displays E07; often linked to DHW sensor or DHW circuit issues on combi models.
DHW NTC / DHW Circuit Fault
E08
Furnace displays E08; often associated with fan or flue sensor issues.
Fan / Flue Monitoring Fault
E09
Furnace displays E09; often related to gas valve or flame control anomalies.
Gas Valve / Flame Control Fault
E10
Furnace displays E10; often associated with internal communication or EEPROM errors.
Internal Control Board Memory / Configuration Fault
Symptom
Domestic hot water temperature fluctuates between hot and cold during a shower on a Sime combi furnace.
Inconsistent DHW Temperature
Symptom
Furnace causes banging or knocking noises in the pipework when starting or stopping.
Water Hammer / Thermal Expansion Noise
Symptom
Furnace emits a high‑pitched whistling noise from the flue or burner area during operation.
Flue Resonance / Gas Flow Whistle
Symptom
Furnace fan runs continuously even when there is no call for heat.
Fan Stuck On
Symptom
Furnace frequently short cycles, turning on and off rapidly without maintaining stable room temperature.
Short Cycling / Oversized or Miscontrolled Operation
Symptom
Furnace frequently trips the household circuit breaker or blows fuses.
Electrical Short / Overcurrent
Symptom
Furnace ignites with a loud boom or pop, sometimes shaking the casing.
Delayed Ignition
Symptom
Furnace is very noisy during operation, with rumbling, whistling, or droning sounds from the burner or fan.
Combustion Noise / Fan Noise
Symptom
Furnace or flue area smells of exhaust fumes or a sharp acidic odor during operation.
Flue Gas Leakage / Poor Combustion
Symptom
Furnace or surrounding area smells of gas, especially near the gas valve or pipe joints.
Gas Leak
Symptom
Furnace runs but produces no heat to the home; blower or pump operates but radiators or air outlets stay cold.
No Heat Output Despite Operation
Symptom
Furnace starts but shuts down after a few minutes without showing an error code; house does not reach set temperature.
Premature Shutdown / Limit Cycling
Symptom
Furnace will not start at all; no display or lights on the control panel.
No Power / Dead Furnace
Symptom
Pressure gauge on the furnace rises rapidly when heating and may trigger the pressure relief valve.
Over‑Pressurization / Expansion Vessel Failure
Symptom
Radiators or heating zones heat unevenly; some remain cold while others are hot.
Poor System Balancing / Air Lock
Symptom
System pressure drops over time without visible leaks; furnace frequently locks out on low pressure.
Chronic Pressure Loss
Symptom
Water is leaking from the bottom of the furnace casing or from connected pipework.
Internal Water Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Furnace attempts to ignite but fails; burner does not light and unit locks out after several tries.
|
Ignition Failure / No Flame Detection | View Details |
| A02 |
Furnace lights briefly then shuts down; flame appears but is lost within a few seconds and the unit locks out.
|
Flame Loss After Ignition | View Details |
| A03 |
Furnace shuts down and displays an overheat/limit error; casing may feel unusually hot and burner will not restart until cooled.
|
Overheat Thermostat Tripped | View Details |
| A04 |
Furnace does not start; display shows low water pressure or lockout related to system pressure.
|
Low System Water Pressure (Hydronic Sime Furnace/Boiler) | View Details |
| A05 |
Furnace locks out with a flue or exhaust fault; fan may run briefly then stop.
|
Flue Gas Exhaust / Fan Fault | View Details |
| A06 |
Furnace shows an ionization or flame signal error even though the burner appears to be lit.
|
Flame Signal Too Weak or Absent | View Details |
| A07 |
Furnace displays a fan speed or fan tachometer error; burner does not ignite.
|
Fan Speed Control / Tachometer Fault | View Details |
| A08 |
Furnace indicates a gas valve or modulation fault; burner may stay at minimum or not light at all.
|
Gas Valve Control / Modulation Error | View Details |
| A09 |
Furnace shows a return sensor or flow sensor error; unit may overheat or shut down prematurely.
|
Flow/Return Temperature Sensor Fault | View Details |
| A10 |
Furnace indicates a domestic hot water (DHW) sensor error on combi models; hot water may be unstable or unavailable.
|
DHW Temperature Sensor Fault | View Details |
| A11 |
Furnace displays a flow switch or flow sensor error; burner will not fire for heating or DHW.
|
Water Flow Detection Fault | View Details |
| A12 |
Furnace shows a flue temperature sensor error; unit may shut down shortly after ignition.
|
Flue Gas Temperature Sensor Fault | View Details |
| A13 |
Furnace indicates a condensate or drain fault; unit may shut down during operation, especially in cold weather.
|
Condensate Drain Blockage | View Details |
| A14 |
Furnace shows a communication error between the main control board and user interface or remote controller.
|
Control Board Communication Fault | View Details |
| A15 |
Furnace indicates a power supply or mains frequency error; unit may not start or may reset intermittently.
|
Mains Voltage / Frequency Fault | View Details |
| E01 |
Furnace displays E01 and will not ignite; often associated with ignition or flame detection problems.
|
General Ignition Lockout | View Details |
| E02 |
Furnace displays E02 and shuts down; often linked to overheat or safety thermostat activation.
|
Safety Thermostat / Overheat Lockout | View Details |
| E03 |
Furnace displays E03 and stops; often associated with flue or air pressure switch problems.
|
Air Pressure Switch / Flue Safety Fault | View Details |
| E04 |
Furnace displays E04; typically related to low water pressure or water circulation issues on hydronic models.
|
Low Water Pressure / Circulation Fault | View Details |
| E05 |
Furnace displays E05; often associated with flow temperature sensor issues.
|
Flow NTC Sensor Error | View Details |
| E06 |
Furnace displays E06; typically related to return temperature sensor problems.
|
Return NTC Sensor Error | View Details |
| E07 |
Furnace displays E07; often linked to DHW sensor or DHW circuit issues on combi models.
|
DHW NTC / DHW Circuit Fault | View Details |
| E08 |
Furnace displays E08; often associated with fan or flue sensor issues.
|
Fan / Flue Monitoring Fault | View Details |
| E09 |
Furnace displays E09; often related to gas valve or flame control anomalies.
|
Gas Valve / Flame Control Fault | View Details |
| E10 |
Furnace displays E10; often associated with internal communication or EEPROM errors.
|
Internal Control Board Memory / Configuration Fault | View Details |
| – |
Domestic hot water temperature fluctuates between hot and cold during a shower on a Sime combi furnace.
|
Inconsistent DHW Temperature | View Details |
| – |
Furnace causes banging or knocking noises in the pipework when starting or stopping.
|
Water Hammer / Thermal Expansion Noise | View Details |
| – |
Furnace emits a high‑pitched whistling noise from the flue or burner area during operation.
|
Flue Resonance / Gas Flow Whistle | View Details |
| – |
Furnace fan runs continuously even when there is no call for heat.
|
Fan Stuck On | View Details |
| – |
Furnace frequently short cycles, turning on and off rapidly without maintaining stable room temperature.
|
Short Cycling / Oversized or Miscontrolled Operation | View Details |
| – |
Furnace frequently trips the household circuit breaker or blows fuses.
|
Electrical Short / Overcurrent | View Details |
| – |
Furnace ignites with a loud boom or pop, sometimes shaking the casing.
|
Delayed Ignition | View Details |
| – |
Furnace is very noisy during operation, with rumbling, whistling, or droning sounds from the burner or fan.
|
Combustion Noise / Fan Noise | View Details |
| – |
Furnace or flue area smells of exhaust fumes or a sharp acidic odor during operation.
|
Flue Gas Leakage / Poor Combustion | View Details |
| – |
Furnace or surrounding area smells of gas, especially near the gas valve or pipe joints.
|
Gas Leak | View Details |
| – |
Furnace runs but produces no heat to the home; blower or pump operates but radiators or air outlets stay cold.
|
No Heat Output Despite Operation | View Details |
| – |
Furnace starts but shuts down after a few minutes without showing an error code; house does not reach set temperature.
|
Premature Shutdown / Limit Cycling | View Details |
| – |
Furnace will not start at all; no display or lights on the control panel.
|
No Power / Dead Furnace | View Details |
| – |
Pressure gauge on the furnace rises rapidly when heating and may trigger the pressure relief valve.
|
Over‑Pressurization / Expansion Vessel Failure | View Details |
| – |
Radiators or heating zones heat unevenly; some remain cold while others are hot.
|
Poor System Balancing / Air Lock | View Details |
| – |
System pressure drops over time without visible leaks; furnace frequently locks out on low pressure.
|
Chronic Pressure Loss | View Details |
| – |
Water is leaking from the bottom of the furnace casing or from connected pipework.
|
Internal Water Leak | View Details |
No matching codes found
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