Modern boilers come in a variety of modifications. Although they differ in structure, causes of malfunctions and maintenance requirements are similar. The most common causes of faults are described in the following table.
Ariston C boilers troubleshooting
| Code | Fault description |
|---|
| A 01 | Overheat lockout |
| A 03 | No flame detected within allowed time |
| A 36 | Flue pipe too high temperature |
| A 37 | CPU fault |
| A 39 | PCB fault 1 |
| A 40 | PCB fault 2 |
| A 41 | Fan error |
| E 02 | No Circulation (check pump and water pressure) |
| E 04 | No flame detection |
| E 05 | Anti-freeze system, pump only |
| E 06 | Anti-freeze system, pump and burner |
| E 07 | No water circulation in primary circuit |
| E 08 | No water in the primary circuit |
| E 11 | Flow sensor open circuit |
| E 12 | Flow sensor short circuit |
| E 13 | Return sensor open circuit |
| E 14 | Return sensor short circuit |
| E 15 | Outdoor sensor open circuit (where fitted) |
| E 16 | Outdoor sensor short circuit (where fitted) |
| E 18 | Flame lift |
| E 20 | Flame detected with gas valve off |
| E 22 | Faulty air pressure switch |
| E 23 | Low fan speed |
| E 25 | Tank sensor open circuit |
| E 26 | Tank sensor short circuit |
| E 27 | Tank fault warning |
| E 29 | Room sensor open circuit |
| E 30 | Room sensor short circuit |
| E 33 | Under floor heating thermostat open circuit |
| E 34 | Flue pipe sensor open circuit |
| E 35 | Flue pipe sensor short circuit |
| E 36 | Flue pipe too high temperature |
| E 37 | Communication problem with the main PCB |
| E 38 | Reset pressed 5 times within 15 minutes |
Ariston E-Combi 24 boilers troubleshooting
| Problem | Cause/Solutions |
|---|
| Insufficient circulation | Water pressure |
| Bleed heat exchanger |
| Pump operation |
| CH return filter for blockages |
| Circulation around boiler (blockages) |
| ntc temperature sensors |
| Insufficient water (request filling) | Water pressure gauge for correct pressure |
| Check for waterleaks on the entire system |
| CH Flow temp, probe circuit open/ short circuit | Check connections and wiring to temp sensors |
| Resistance values of temp sensors |
| Heating delivery probe problem | Details in maintenance guide in installation manual |
| Floor thermostat contact open | Check terminals TA2 for presence of link wire |
| EEPROM Error | Check the EEPROM connection onto the pcb |
| Communication error | Check connection and wiring onto all devices, main and display pcb |
| Too many (>5) resets in 5 minutes | Identify reason for lockout from table and check for relevant faults |
| No Flame detected | Insufficient working gas pressure |
| 1st Ignition failed | Spark electrode/wiring connectors |
| 2nd Ignition failed | Ignition electrode/wiring connectors |
| Flame cut-off | Spark generator/wiring connectors |
| Check flue system for correct assembly/ termination |
| Check earth |
| Gas valve |
| C02 settings |
| Soft light rate |
| Flame detected with gas valve closed | Ignition electrode/wiring connectors |
| Ignition electrode wiring connection onto main pcb |
| Flame lift | Insufficient working gas pressure |
| Check flue system for correct assembly/ termination |
| C02 settings |
| Thermofuse open | Check wiring and connections to thermofuse |
| Check integriry of main heat exchanger |
| Fan speed error | Check fan |
| Check wiring connections from fan to pcb |
Ariston GENUS HE 35 Plus boilers troubleshooting
| Display | Cause |
|---|
| A01 | Three ignition attempts |
| A03 | The output temperature exceeds 105°C during operation |
| A07 | Too many flame separations over a period during operation |
| A17 | Input water circulation fault |
| A18 | No water circulation |
| A33 | Fan problem |
| A97 | Electronic control problem |
| A98 |
| A99 | Electronic control problem |
| SOI | Flame not detected on first attempt |
| S 02 | Flame not detected on second attempt |
| S 04 | Open circuit on Domestic hot water sensor |
| S 05 |
| S 06 | Flame separation |
| S 25 | Tank sensor open |
| S 26 | Tank sensor short circuit |
| S27 | Tank overheating |
| S 30 | External sensor open circuit |
| S31 |
| S 80 | Open circuit or short circuit on room sensor of the Clima Manager remote control |
| E 02 | Insufficient water pressure |
| E 06 | Open circuit on heating outlet sensor |
| E 07 |
| E 08 |
| E 09 |
| e no | Contact open in the floor overheat safety device circuit (Flora room thermostat) |
| E 20 | False flame detection with gas valve closed |
| E 94 | Electronic control problem |
| E 95 | Read error in heating outlet and return sensors |
| E 99 | 5 resets in less than 15 minutes. Resetting by a boiler ON/OFF operation |
Ariston microGENUS II 24 MFFI boilers troubleshooting
| Code | Cause |
|---|
| A01 | No flame after safety time (7 seconds) |
| A03 | The heating flow temperature exceeds 103°C during operation |
| A97 | Problem with the electronic monitoring |
| A98 |
| A99 |
| E02 | Insufficient water pressure |
| E04 | Domestic hot water temperature probe in open circuit |
| E05 | Domestic hot water temperature probe short circuited |
| E06 | Heating flow temperature probe in open circuit |
| E07 | Heating flow temperature probe short circuited |
| E08 | Heating return temperature probe in open circuit |
| E09 | Heating return temperature probe short circuited |
| E20 | Flame detected with gas valve closed |
| E21 | Error in the electrical connection (live and neutral crossed) |
| E33 | The air pressure switch is closed before the ignition sequence |
| E34 | The air pressure switch does not close when the fan runs |
| E99 | More than 5 RESETS of the boiler in 15 minutes. |