Ignition Failure — No Flame After 5 Attempts
The most common ATAG fault code. The boiler has failed to ignite after 5 attempts. Frequently caused by a frozen condensate pipe in cold weather. ATAG 133 is equivalent to code 133 on Navien and Baxi boilers.
Code 133 in winter on ATAG boilers is very commonly caused by a frozen condensate drain. Thaw before resetting.
Step-by-Step Fix Guide
-
Step 1
Check gas supply — try other gas appliances
-
Step 2
In cold weather, check the condensate pipe for ice and thaw with warm water
-
Step 3
Reset the boiler
-
Step 4
If fault persists, call a Gas Safe engineer to check the ignition system
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.