Fault Code |
Boiler Model |
Possible Cause |
Central Heating Circuit |
101 |
All Boilers |
Overheat |
102 |
E-Combi Evo
E-System Evo
Clas He Evo (Combi and system) |
Pressure sensor error |
103 |
All Boilers |
Insufficient circulation |
104 |
All Boilers |
Insufficient circulation |
105 |
All Boilers |
Insufficient circulation |
106 |
All Boilers |
Insufficient circulation |
107 |
All Boilers |
Insufficient circulation |
108 |
All Combi Boilers |
Insufficient water (request filling) |
109 |
Clas net one / Clas one Combi
Clas system one |
System pressure greater than 3 bar |
110 |
All Boilers |
Central heating Flow temperature probe circuit open / short circuit |
112 |
All Boilers |
Central heating return temperature probe circuit open / short circuit |
114 |
All Boilers |
External sensor circuit open / short circuit |
116 |
All Combi and System Boilers |
Floor thermostat contact open |
118 |
All Boilers |
Heating delivery probe problem |
1p1 |
All Boilers |
Insufficient circulation indication |
1p2 |
All Boilers |
Insufficient circulation indication |
1p3 |
All Boilers |
Insufficient circulation indication |
1p4 |
Clas Net one Combi
Clas one Combi
Clas System one |
Insufficient circulation indication |
D.H.W Circuit |
202 |
Clas HE evo
Clas he evo system
E-combi evo
E-system evo |
2 bottom storage temperature probe open/short circuit |
204 |
Clas HE evo
Clas he evo system
E-combi evo
E-system evo |
Solar collector temperature probe open/short circuit |
205 |
E-combi one
E-System one
Clas Net one Combi
Clas one Combi |
Domestic hot water in probe open circuit |
207 |
Clas HE evo
Clas he evo system
E-combi evo
E-system evo |
Solar collector overheating |
208 |
Clas HE evo
Clas he evo system
E-combi evo
E-system evo |
Collector frost protection temperature |
Internal printed circuit board (PCB) |
301 |
All Boilers |
EEPROM error |
302 |
All Boilers |
Communication error |
303 |
All Boilers |
Main printed circuit board (PCB) error |
304 |
All Boilers |
Too many resets (> 5) in 15 minutes |
305 |
All Boilers |
Main printed circuit board (PCB) error |
306 |
All Boilers |
Main printed circuit board (PCB) error |
307 |
All Boilers |
Main printed circuit board (PCB) error |
3P9 |
E-combi one
E-System one
Clas Net one Combi
Clas one Combi
Clas System one |
Schedule service |
External printed circuit board (PCB) |
407 |
Clas HE evo
Clas he evo system
E-combi evo
E-system evo |
7 Room sensor circuit open/short circuit |
Ignition and Detection |
501 |
All Boilers |
No flame detected |
502 |
All Boilers |
Flame detected with gas valve closed |
504 |
All Boilers |
Flame lift |
5P1 |
All Boilers |
1st ignition failed |
5P2 |
All boilers |
2nd ignition failed |
5P3 |
All Boilers |
Flame cut-of |
Air Inlet / Flue gas outlet |
604 |
CLAS HE R
E-Combi Evo
E-System EVO
Clas HE evo Combi
Clas HE evo System |
Insufficient fan speed |
610 |
All Boilers |
Thermofuse open |
612 |
Clas HE Evo Combi
Clas He Evo System
E-Combi Evo
E-system Evo
Clas net one combi
Clas one combi
Clas system one |
Fan speed has incorrect measurement |
Multi-zone Heating |
701 |
E-Combi Evo
E-System EVO
Clas HE evo combi
Clas he evo system |
Zone 2 outgoing sensor defective |
702 |
E-Combi Evo
E-System EVO
Clas HE evo Combi
Clas HE evo System |
Zone 2 return sensor defective |
703 |
E-Combi Evo
E-System EVO
Clas HE evo combi
Clas he evo system |
Zone 3 outgoing sensor defective |
704 |
E-Combi Evo
E-System EVO
Clas HE evo Combi
Clas HE evo System |
Zone 3 return sensor defective |
705 |
E-Combi Evo
E-System EVO
Clas HE evo combi
Clas he evo system |
Hydraulic separation sensor defective |
706 |
E-Combi Evo
E-System EVO
Clas HE evo combi
Clas he evo system |
Zone 2 overheating |
707 |
E-Combi Evo
E-System EVO
Clas HE evo Combi
Clas HE evo System |
Zone 3 overheating |