Boiler
E7
The E7 error code on a Baxi boiler indicates a fan or air pressure fault — it’s a safety lockout that stops the boiler firing until the underlying issue is resolved. Don’t ignore it: a boiler running with a faulty fan risks incomplete combustion and carbon monoxide exposure.
What does this error mean?
Your Baxi boiler continuously monitors the fan and the air pressure switch (also called the pressostat) to confirm that dangerous flue gases are being safely expelled before ignition occurs. The E7 code means the boiler’s control board has detected that the fan isn’t running at the correct speed, or that the air pressure switch hasn’t confirmed adequate airflow. As a safety measure, the boiler locks out and won’t attempt to light until airflow is verified.
Est. repair cost
£80–£350 for professional repair (fan or pressure switch); new boiler £1,800–£3,500 installed
🔍 Likely causes
🛠️ Step-by-step fix
Step 1 — Reset the boiler: Press and hold the reset button (usually marked with a flame or ‘R’) for 3–5 seconds. If the boiler fires up and stays on, monitor it closely for 24 hours. A one-off lockout can occur after a power cut or brief fault.
Step 2 — Check the flue terminal externally: Go outside and visually inspect the boiler’s flue outlet (the white or grey pipe on your external wall). Check for obvious blockages like a bird’s nest, leaves, or damage. Do not attempt to clear blockages yourself inside the flue.
Step 3 — Check the condensate pipe: Locate the condensate pipe (usually a white plastic pipe running to an outside drain or internal waste pipe). In cold weather, this pipe can freeze and cause boiler faults — pouring warm (not boiling) water over the external section can thaw it.
Step 4 — Check your gas supply: Confirm your gas supply is working by testing another gas appliance (e.g. hob). If there’s no gas at all, contact your gas supplier immediately.
Step 5 — Stop here and call a Gas Safe engineer: If the reset doesn’t hold and the E7 returns, the fault is almost certainly internal — a failed fan, pressure switch, wiring issue, or PCB. These components involve gas and electrical systems inside the boiler and must only be diagnosed and replaced by a Gas Safe registered engineer.
📞 When to call a professional
Call a Gas Safe registered engineer if the E7 error returns after a reset, or if you smell gas or suspect a flue blockage you cannot safely see from outside. Tell the engineer: ‘My Baxi boiler is showing an E7 fault code — I suspect a fan or air pressure switch issue.’ This helps them arrive with the right parts and cuts your call-out time.
⚖️ Repair or replace?
Fan replacement on a Baxi boiler typically costs £150–£350 including parts and labour; an air pressure switch is cheaper at £80–£180 fitted. If your boiler is over 10–12 years old, weigh repair costs against a new boiler (£1,800–£3,500 installed) — repeated faults on an older boiler make replacement the more cost-effective long-term choice. Baxi boilers under 7 years old in reasonable condition are almost always worth repairing.