How to Fix Baxi E28 Fault Code (UK)
Baxi showing E28 — Flue sensor. UK diagnosis, likely spare (flue NTC) and step-by-step reset.
Baxi
What the code means
E28 on a Baxi indicates flue sensor. The boiler locks out to protect the heat exchanger and, on gas faults, to comply with the Gas Safety (Installation and Use) Regulations. Always reset to confirm the code is live, not historical.
Likely spare
The most common fix is the flue NTC. Check the exploded diagram against the GC number on the data plate before ordering — Baxi revised parts on Baxi units mid-production.
Fix procedure
Replace flue NTC. Baxi 720873501.
Log the fault and reset. If the code returns within 24 hours, escalate to full electrical diagnosis with a manometer and multimeter.
Frequently asked questions
- Can I reset E28 myself?
- You can press the reset button up to 3 times. If E28 returns, the boiler needs a Gas Safe engineer — it is illegal to repair gas components without registration.
- Is the part covered under warranty?
- Baxi standard warranty is 2–10 years depending on model. Registered installations get the full term. Check the sticker inside the case.
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