Atag Fault Codes

Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.


10LinkOutside sensor error
20LinkFlow sensor error
40LinkReturn sensor error
50LinkDomestic hot water (DHW) sensor errorIC, IS
61LinkBus communication error
78LinkWater pressure out of range
105LinkVenting program active when power turned on / interrupted (runs for 7 mins)Ê
110LinkExceeded safety temperature
111LinkExceeded maximum pressure
119LinkX2 link position 4 and 5 missing
129LinkFan doesnÕt start
133LinkNo flame after 5 ignition attempts
151LinkFan error or control unit defective (speed control is not achieved)Ê
154LinkReturn greater than flow Ð flow temperature increases too fast
101LinkOverheat error
102LinkPressure sensor fault
104LinkFlow check failed
108LinkPressure needs filling to < 0.5 bar
1P4LinkPressure needs filling to 0.5 Ð 0.8 bar
109LinkPressure > Pmax error
110LinkSend probe damaged
112LinkReturn probe error Ð could be damanged
114LinkOutdoor sensor error Ð could be damaged
117LinkPressure greater than 3 bar or pump pressure increase is too highIC, IS
118LinkPressure less than 1 bar or pump pressure increase too low (no pump detection).IC, IS
133LinkNo flame after 5ÊignitionÊattempts
141LinkCentral heating flow switch is open
201LinkDomestic hot water (DHW) probe damaged
203LinkTank probe damaged
303LinkPrinted circuit board (PCB) error
304LinkToo many resets have occured
501LinkNo flame detected
612LinkFan fault Ð fan isnÕt starting up

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