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JamesI, Handyman
Category: Appliance
Satisfied Customers: 2086
Experience:  I have repaired and maintained numerous items over the years, from fridges to freezers, radios to TV's.
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I have a fault code bL81 on my ATAG E32S boiler, the BrainQ

Customer Question

I have a fault code bL81 on my ATAG E32S boiler, the BrainQ also shows this. I can find no reference to what this is, clearly a sensor is reading a fault but I'm unsure which, I found a reference to a gas flue sensor but can't see anything attached to the flue. Any ideas what it might be?
Submitted: 1 year ago.
Category: Appliance
Expert:  JamesI replied 1 year ago.

BL = Blocked, 81 = flue gas sensor.
So your right in that you need to check the flue gas sensor is connected \ operational, as the boiler has locked the burner until the fault is cleared.

The repair and diagnostics must be performed by a Gas Safe engineer, who will find it by tracing where the wires on pins 3 and 5 goto on connector X10 (see attached diagram), the sensor should be located near the condensate tray, in the centre of the boiler which leads to the flue.