Biasi is an Italian heating manufacturer whose compact combi boilers are commonly found in UK social housing, flats, and smaller properties. Their Riva range is particularly well-known. Biasi fault codes use a combination of letters and numbers.
Biasi Boiler Fault Codes
All Biasi Fault Codes 38
| Code | Fault | Severity | Type | View guide |
|---|---|---|---|---|
| A1 | Gas Valve Fault The gas valve has a fault — not responding to control commands correctly. | High | Engineer | View Guide |
| E1 | Low Water Pressure The system water pressure has dropped below the safe minimum on Biasi boilers. | Low | DIY Check | View Guide |
| E10 | Return Temperature Sensor Fault The return NTC temperature sensor has developed a fault. | Medium | Engineer | View Guide |
| E11 | False Flame Signal The boiler is detecting a flame when the gas valve is closed. This is a… | High | Engineer | View Guide |
| E12 | DHW Temperature Sensor Fault The domestic hot water NTC temperature sensor is faulty. | Medium | Engineer | View Guide |
| E13 | Fan Speed Fault The fan is running outside its expected speed range. | High | Engineer | View Guide |
| E14 | Gas Valve Fault The gas valve is not responding correctly to commands from the PCB. | High | Engineer | View Guide |
| E15 | PCB Fault The printed circuit board has an internal fault. | High | Engineer | View Guide |
| E16 | Condensate Trap Full / Blocked The condensate trap is full or the drain pipe is blocked. Condensate cannot drain freely. | Medium | DIY Check | View Guide |
| E17 | Low Water Pressure The system water pressure is below the minimum operating level. | Low | DIY Check | View Guide |
| E18 | Gas Valve Fault Gas valve not responding to commands. | High | Engineer | View Guide |
| E19 | Pump Fault Pump not running or seized. | High | Engineer | View Guide |
| E2 | Safety Thermostat Activated The boiler has overheated and the safety thermostat has cut out to prevent damage. | High | Engineer | View Guide |
| E20 | PCB Communication Error Internal PCB communication fault. | High | Engineer | View Guide |
| E21 | Low Gas Pressure Insufficient gas supply pressure. | High | Engineer | View Guide |
| E22 | Diverter Valve Fault Valve stuck or not switching. | Medium | Engineer | View Guide |
| E23 | Rapid Temperature Rise Flow temp rising too quickly. | High | Engineer | View Guide |
| E24 | Flow/Return Differential Fault Temperature gap abnormal. | Medium | Engineer | View Guide |
| E25 | Outdoor Sensor Fault Outdoor sensor faulty. | Low | Engineer | View Guide |
| E26 | eBUS Fault Communication fault. | Medium | Engineer | View Guide |
| E27 | Combustion Fault Air/gas mixture outside limits. | High | Engineer | View Guide |
| E28 | Flame Detected After Shutdown Flame signal with gas valve closed. | High | Engineer | View Guide |
| E29 | EEPROM Error PCB memory error. | High | Engineer | View Guide |
| E3 | Overheat Fault The boiler has overheated and the safety thermostat has activated. | High | Engineer | View Guide |
| E30 | Mains Voltage Fault Voltage outside range. | Medium | Engineer | View Guide |
| E31 | Frost Protection Active Frost protection running. | Medium | DIY Check | View Guide |
| E32 | Flue Gas Overheat Flue gas too hot. | High | Engineer | View Guide |
| E33 | APS Fault Air pressure switch fault. | High | Engineer | View Guide |
| E34 | Pressure Sensor Fault Electronic sensor faulty. | Medium | Engineer | View Guide |
| E35 | Coding Plug Fault Coding plug unreadable. | High | Engineer | View Guide |
| E4 | Fan Fault / Air Pressure Switch The fan is not operating correctly or the air pressure switch is not confirming airflow. | High | Engineer | View Guide |
| E5 | NTC Sensor Fault A temperature sensor (NTC thermistor) has a fault — either the flow or return sensor. | Medium | Engineer | View Guide |
| E6 | False Flame Detected The boiler's ionisation circuit has detected a flame when the gas valve should be closed. | High | Engineer | View Guide |
| E7 | PCB / Electronics Fault The main PCB has detected an internal fault. | High | Engineer | View Guide |
| E8 | Flow Temperature Sensor Fault The flow NTC temperature sensor has a short circuit or open circuit. | Medium | Engineer | View Guide |
| E9 | Flue/Exhaust Temperature Fault The flue gas temperature has exceeded safe limits, or there is an issue with the… | High | Engineer | View Guide |
| I1 | Ignition Failure / No Flame The most common Biasi fault code — the boiler has failed to ignite or lost… | Medium | DIY Check | View Guide |
| I2 | Overheat Lockout (Severe) A severe overheat lockout that requires manual reset — more serious than E3. | High | Engineer | View Guide |