Fault Code Possible Fault
H.01 – .00 Temporary Fault – Temporary loss of communication between gas valve and boiler board. Fault in air/gas unit.
Loose connection to gas valve.
H.01 – .05 Temporary Fault – Maximum difference between the flow and return temperature exceeded. Non-existent or insufficient circulation. Sensor error.
H.01 – .08 Temporary Fault – Flow temperature increasing too fast in heating mode. Non-existent or insufficient circulation.
Sensor error.
H.01 – .14 Temporary Fault – Maximum flow temperature value exceeded. Non-existent or insufficient circulation. Non-existent or insufficient circulation.
H.01 – .18 Temporary Fault – No circulation of water. Non-existent or insufficient circulation. Sensor error.
H.01 – .21  Temporary Fault – Flow temperature increasing too fast in DHW mode. Non-existent or insufficient circulation. Sensor error.
H.02 – .02 Temporary Fault – No input of parameters C1/C2. PCB not configured.
H.02 – .03 Temporary Fault- Incorrect configuration settings C1/C2.
H.02 – .04 Temporary Fault – Parameter error. Incorrect parameters.
H.02 – .06 Temporary Fault – System water pressure. Water leak on boiler. Water leak on system.
H.03 -.00 Temporary Fault – Communication error with NTC flue sensor. Sensor not, or badly connected. Bad connection. Sensor fault.
H.03 – .01 Temporary Fault – Communication error with the HMI PCB. HMI not connected.
H.03 – .02 Temporary Fault – No flame during operation. No ionization current.
E.00 – .04 Permanent Fault –  Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection. Sensor fault.
E.00 – .05 Permanent Fault – Return temperature sensor short-circuit. Sensor not or badly connected. Bad connection. Sensor fault.
E.01 – .02 Permanent Fault – Temperature measured by return sensor greater than flow sensor. Bad connection. Sensor fault. Sensor not or badly connected.
E.01 – .04 Permanent Fault – Loss of flame detected 5 times in 24 hours (With burner on). No ionization current.
E.01 – .11 Permanent Fault Requiring Reset – Incorrect fan speed. External draught over the boiler. Defective gas/air unit.
E.01 – .12 Permanent Fault Requiring Reset – Temperature measured by return sensor greater than flow temperature.
E.01 – .17 Permanent Fault Requiring Reset – No circulation. Sensor not or badly connected. Sensor fault.
E.01 – .20 Permanent Fault  – Maximum flue gas temperature value reached (>140 Deg C). No circulation. Sensor fault.
E.02 – .00 Permanent Fault  – Boiler reset in progress. Reset button has been pressed.
E.02 – .07 No or low system water pressure. Low system pressure (less than 0.5bar) boiler will not function.
E.02 – .16 Permanent Fault –  On board CSU time-out. Check PCB for damage.
E.02 – .17 Permanent Fault – Permanent loss of communication between gas valve and boiler PCB. Fault in air/gas unit. Loose connection to gas valve.
E.02 – .19 Permanent Fault – Jumper 1 changed. Check position of jumper 1.
E.02 – .20 Permanent Fault – Jumper 2 changed. Check position of jumper 2.
E.02 – .21 Permanent Fault – Jumper 3 changed. Check position of jumper 3.
E.02 – .47 Permanent Fault – Connection to external device unsuccessful. Check wiring to external device.
E.02 – .48 Permanent Fault – Configuration to external device unsuccessful. Check pairing to external.
E.04 – .00 Permanent Fault  – Gas valve fault. Gas valve not detected.
E.04 – .01 Permanent Fault  – Flow temperature sensor short-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .02 Permanent Fault  – Flow temperature sensor open-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .03 Permanent Fault – Critical flow temperature reached. Non-existent or insufficient circulation.
E.04 – .04 Permanent Fault  – Flue temperature sensor short-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .05 Permanent Fault – Flue temperature sensor open-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .06 Permanent Fault – Critical flue gas temperature value reached. No circulation. Sensor fault.
E.04 – .08 Permanent Fault – Maximum safe temperature value reached. (Safety thermostat open-circuited). No circulation. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .10 Failure to light (could be gas supply issue).
E.04 – .12 Permanent Fault – False flame signal. Short-term fluctuation of the mains. Ionization current present even though there is no flame. The burner remains very hot (CO2 too high). Defective gas/air unit.
E.04 – .13 Permanent Fault – Fan rotor blocked. Fan seized. Wiring to fan damaged.
E.04 – .17 Permanent Fault – Problem with gas valve. Defective gas/air unit.