Sime is an Italian boiler manufacturer with over 40 years of history. Their Format, Friendly, Murelle, Dewy, and Planet ranges are found in UK homes and light commercial properties. Known for reliable Italian engineering, Sime boilers use alarm codes prefixed with ‘AL’ or ‘E’ depending on the model generation.
Sime Boiler Fault Codes
All Sime Fault Codes 30
| Code | Fault | Severity | Type | View guide |
|---|---|---|---|---|
| AL 01 | Smoke Thermostat (Alarm 01) The flue gas temperature has exceeded the safe limit. | High | Engineer | View Guide |
| AL 02 | Low Water Pressure (Alarm 02) System pressure is below the minimum. The boiler has locked out. | Low | DIY Check | View Guide |
| AL 04 | DHW Sensor Fault (Alarm 04) The domestic hot water NTC sensor has developed a fault. | Medium | Engineer | View Guide |
| AL 05 | Flow Sensor Fault (Alarm 05) The central heating flow NTC sensor is faulty. | Medium | Engineer | View Guide |
| AL 06 | No Flame Detection (Alarm 06) No flame detected during ignition. | High | Engineer | View Guide |
| AL 07 | Safety Thermostat (Alarm 07) The safety thermostat has activated. | High | Engineer | View Guide |
| AL 09 | Fan Fault (Alarm 09) Fan not running correctly. | High | Engineer | View Guide |
| AL 10 | Return Sensor Fault (Alarm 10) Return NTC sensor faulty. | Medium | Engineer | View Guide |
| AL 24 | Flow Sensor Short (Alarm 24) The flow NTC has a short circuit. | Medium | Engineer | View Guide |
| AL 25 | DHW Sensor Short (Alarm 25) The DHW NTC has a short circuit. | Medium | Engineer | View Guide |
| AL 27 | Compatibility Error (Alarm 27) The PCB configuration does not match the boiler hardware. | High | Engineer | View Guide |
| AL 29 | PCB Fault (Alarm 29) Internal PCB error. | High | Engineer | View Guide |
| AL 31 | Communication Fault (Alarm 31) Internal communication error between boiler components. | High | Engineer | View Guide |
| AL 32 | Combustion Fault (Alarm 32) Combustion quality is outside the permitted range. | High | Engineer | View Guide |
| E01 | Ignition Failure The boiler has failed to ignite. This is the most common Sime fault code. | High | Engineer | View Guide |
| E02 | Overheat Protection The safety thermostat has activated due to overheating. | High | Engineer | View Guide |
| E03 | Fan Fault The fan is not running at the expected speed. | High | Engineer | View Guide |
| E04 | DHW Sensor Fault The domestic hot water NTC sensor has a fault. | Medium | Engineer | View Guide |
| E05 | Flow Sensor Fault The central heating flow NTC sensor is faulty or has an open circuit. | Medium | Engineer | View Guide |
| E06 | No Flame Detection The ionisation electrode cannot detect a flame during the ignition sequence. | High | Engineer | View Guide |
| E07 | Safety Thermostat Intervention The safety thermostat has cut out — similar to E02 but a different trigger circuit. | High | Engineer | View Guide |
| E08 | Air Pressure Switch Fault The air pressure switch is not confirming correct airflow. | High | Engineer | View Guide |
| E09 | Gas Valve Fault The gas valve is not opening or closing correctly. | High | Engineer | View Guide |
| E10 | Return Sensor Fault The return water NTC sensor is faulty. | Medium | Engineer | View Guide |
| E11 | PCB Fault The printed circuit board has an internal error. | High | Engineer | View Guide |
| E12 | Pump Fault The circulation pump is not running or is blocked. | High | Engineer | View Guide |
| E13 | Low Water Pressure System pressure has dropped below the safe operating level. | Low | DIY Check | View Guide |
| E14 | Condensate Blocked The condensate drain pipe is blocked or frozen. | Medium | DIY Check | View Guide |
| E15 | Diverter Valve Fault The diverter valve is stuck or not switching correctly. | Medium | Engineer | View Guide |
| E16 | Flame Lost During Operation The flame was established but lost during running. | High | Engineer | View Guide |