BoilerFaultCodesYour boiler has detected a blockage in the flue pipe that is preventing waste gases from safely exiting your home.
Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.
Technical description: Obstruction fumes alarm
What causes this fault?
This fault occurs when the boiler's internal sensors detect that harmful exhaust gases are not able to leave the building freely. The most common reasons are a physical obstruction in the flue pipe, such as a bird's nest or debris, or a mechanical failure in the fan that pushes the air out.
This fault is more frequent during autumn and winter when falling leaves or nesting birds are more likely to block the external vent.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E086 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.