Common ATAG boiler error codes

Welcome to the Maintracts Services blog, your trusted source for all your ATG boiler needs! With over four decades of experience since our establishment in 1974, Maintracts Services has become a leading name in the heating industry.

Our team of expert heating engineers possesses extensive knowledge and expertise in dealing with ATG boilers, offering a comprehensive range of services including installation, maintenance, and repair. In today’s blog post, we will be delving into a topic that is crucial for every ATG boiler owner or technician to understand: common ATG boiler error codes.

These error codes can be perplexing, but worry not! We are here to provide you with valuable insights into what these error codes signify and how to effectively troubleshoot them.

Whether you’re a homeowner, a landlord, or a heating professional, join us as we unravel the mysteries of ATG boiler error codes and help you maintain optimal performance and reliability for your heating system.

ATAG boiler error codes

When an error occurs with your ATAG boiler, you will encounter an error symbol like the one depicted above. Typically, this symbol is accompanied by one of the codes listed in the tables below.

Fault code	System behaviour
10	Outside sensor error
20	Flow sensor error
40	Return sensor error
61	Bus communication error
78	Water pressure out of range
105	Venting program active when power turned on / interrupted (runs for 7 mins)
110	Exceeded safety temperature
111	Exceeded maximum pressure
119	X2 link position 4 and 5 missing
129	Fan doesn’t start
133	No flame after 5 ignition attempts
151	Fan error or control unit defective (speed control is not achieved)
154	Return greater than flow – flow temperature increases too fast
101	Overheat error
102	Pressure sensor fault
104	Flow check failed
108	Pressure needs filling to < 0.5 bar
1P4	Pressure needs filling to 0.5 – 0.8 bar
109	Pressure > Pmax error
110	Send probe damaged
112	Return probe error – could be damanged
114	Outdoor sensor error – could be damaged
141	Central heating flow switch is open
201	Domestic hot water (DHW) probe damaged
203	Tank probe damaged
303	Printed circuit board (PCB) error
304	Too many resets have occured
501	No flame detected
612	Fan fault – fan isn’t starting up

IC & IS Combi Boiler Error Codes

Fault code	System behaviour
50	Domestic hot water (DHW) sensor error
117	Pressure greater than 3 bar or pump pressure increase is too high
118	Pressure less than 1 bar or pump pressure increase too low (no pump detection).

Other Fault Codes

If you come across a spanner symbol, it could indicate one of two possibilities. Firstly, it may signify that your boiler is in service mode. Secondly, it could indicate a blockage issue.

In the case of a blockage, the code is typically temporary and will clear itself or will eventually lock the boiler after several repeated attempts if the error persists.

ATAG Error code 133

When encountering error code 133, it indicates that your boiler’s flame is failing to ignite after five attempts. This issue is commonly attributed to a frozen condensate drain pipe. Fortunately, a frozen condensate pipe is often a simple problem to resolve.