ATAG Boiler Error Codes / Fault Codes Re July 15, 2021

ATAG Boiler Error Codes / Fault Codes


ATAG insists that their boilers are installed and commissioned to the highest standard and that they take great care regarding how their boilers are installed to ensure you get the maximum benefits from your ATAG boiler. Even boilers manufactured to the highest specification will sometimes encounter an issue.

This article will help you identify your boiler’s error and fault codes so that you can inform your Gas Safe Engineer what the issue is.

Many may not have heard about ATAG boilers, however, they have been designing and manufacturing boilers for almost 70 years. During this time, they have set the highest standard for energy efficiency and engineering excellence across the world.

ATAG feel that they stand out from the rest by operating in many different countries across the world. ATAG claim to offer the most energy-efficient boilers in Europe with the lowest NOx emissions, meaning they’re kinder to the environment.

Fitted in each boiler is an iCon heat exchanger, which maintains 98% of its original efficiency levels throughout its lifetime, helping to lower your energy bills. No wonder so many customers love their ATAG boiler.

ATAG boilers are installed in large commercial buildings, as well as in domestic properties. They are trusted by many to deliver high performance, efficiency, and supreme reliability. This explains why ATAG boilers are the number one boiler choice for professionals such as architects and design engineers. In addition to winning numerous global awards, UK consumers also rate ATAG the number one boiler manufacturer on independent review site Trustpilot.

To learn more about ATAG and its history, you can visit its website.

The benefits of having an ATAG boiler installed: 

  • Quiet operation
  • 4 different boiler models 
  • Reliable and efficient 
  • Compact design
  • User friendly
  • Comes with a standard 10-year warranty but can be extended to 14

When looking at Trustpilot, ATAG has been awarded a fantastic 4.9 stars out of 5 and has over 3.8k reviews. 99% of ATAG’s reviews are above average, showing that although ATAG boilers may not be a well-known boiler brand, those who have an ATAG are more than happy with their performance and reliability. 

Here are what ATAG’s customers have had to say about their boilers and ATAG as a brand: 

“The boiler has performed noticeably better than our previous condensing boiler and benefitted from valuable technical support from the ATAG Team”. 

“Excellent boiler which is very efficient – already saving money on our bills”

“Highly recommended, reliable, easy, economical and good customer service”.

If you are looking for a new or replacement cost-effective boiler, but you’re unsure what boiler model you need, we have listed a few of our other blogs below that may be able to help:

If you suspect an issue with your ATAG boiler, we have provided a list of their fault/error codes that could help you to identify the issue and potentially point it out to your Gas Safe Engineer.


ATAG boiler error codes

Fault CodeSystem Behaviour
10Outside sensor error
20Flow sensor error
40Return sensor error
61Bus communication error
78Water pressure out of range
105Venting program active when power turn on/ interrupted (runs for 7 mins)
110Exceeded safety temperature
111Exceeded maximum pressure
119X2 link positions 4 and 5 are missing
129Fan doesn’t start
133No flame after 5 ignition attempts
151Fan error or control unit defective (speed control is not achieved)
154Return greater than flow – flow temperature increases too fast
101Overheat error
102Pressure sensor fault
104Flow check failed
108Pressure needs filling
1P4Pressure needs filling to 0.5 – 0.8 bar
109Pressure > Pmax error
110Send probe damaged
112Return probe error – could be damaged
114Outdoor sensor error – could be damaged
141Central heating flow switch is open
201Domestic hot water (DHW) probe damaged
203Tank probe damaged
303Printed circuit board (PCB) error
304Too many resets have occurred
501No flame detected
612Fan fault – fan isn’t starting up

iC & iS Combi Boiler Error Codes

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

ATAG Error code 133

If you are seeing the error code 133, your boiler’s flame is failing after 5 ignition attempts. This could be down to your condensate pipe freezing. A frozen condensate pipe is something that is often easily fixed, you can find out how in this guide to defrosting a condensate pipe.

Other Fault Codes

If you see a spanner symbol this could be one of two things:

  • Firstly it could mean your boiler is in service mode.
  • Secondly, it could be blocking, if the boiler is blocking the code is only temporary and will clear itself or will lock the boiler after several attempts if the error keeps on occurring.

If you’ve reached the end of this blog and still feel like you may benefit more from having a new boiler installed, then get a boiler quote from WarmZilla today! You can get a quote for a brand spanking new boiler in just a few minutes.

All you need to do is answer some simple questions online about your current boiler, your home demands, and we will provide you with a list of suitable boilers for your home. We also offer a Best Price Guarantee, ensuring that we will beat any competitors by £50 if you manage to find a boiler cheaper elsewhere (which you won’t 😉).