BoilerFaultCodesYour boiler has detected an internal sensor or pressure issue and has stopped working to protect itself.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Thermostat faulty or air pressure switch connection fault
What causes this fault?
This fault happens when the boiler's internal computer receives conflicting information from its temperature sensors or the switch that monitors airflow. Essentially, the boiler can no longer confirm that it is safe to light the burner or that it can accurately track the water temperature, so it shuts down as a safety precaution. The most common trigger is a worn-out sensor or a loose electrical connection within the internal wiring.
This fault can occasionally surface during very windy weather, as extreme gusts can sometimes interfere with the air pressure switch's ability to monitor the flue correctly.
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 Neon3 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Ultimate 30ff is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.