E28 Baxi
Baxi E28 Error: Fan Fault Explained
E28 on a Baxi is the fan fault on most models: the boiler's fan failed to run or to prove the airflow the safety chain requires before ignition, so the boiler is refusing to light. As on every modern boiler, that refusal is the safety system working — combustion without a guaranteed flue path is the outcome the interlock exists to prevent.
What the E28 code means
The pre-ignition sequence demands proof: fan up, airflow confirmed via the pressure-sensing arrangement, and only then gas. E28 records the proof failing — no fan, insufficient fan, or no confirmation. The Baxi/Potterton platform expresses the same logic across both badges, and the fan-and-switch assembly is among the most-replaced components on the family, meaning diagnosis and parts are as routine as boiler work gets.
What you can safely do yourself
Two minutes of checks, then the phone. Power: confirm the boiler's fused spur or plug is on and no RCD has tripped — a dead display with a 'fan' history is sometimes just electrics. Flue: glance at the outside terminal for obstructions after storms or snow. Reset: once, listening for the pre-ignition fan whirr. A fan that won't spin, screeches, or runs without satisfying the boiler (which then locks out anyway) is a component diagnosis for an engineer.
Don't run repeated resets against a fan code — the boiler is interlocked against firing without proven airflow precisely because combustion without a working flue path is dangerous. This is one of the fault families where the safety system doing its job looks identical to an inconvenience; treat it as the former.
What causes it
The family rota: fan wear (bearings and windings ageing — audible as labouring, screeching or silence where the pre-ignition whirr belongs), air pressure switch or sensing tube faults (the healthy-fan-but-lockout signature), flue obstructions after storms or heavy snow, wiring and connector issues, and PCB involvement in the tail. On the rental-weighted installed base, fans that have run unserviced for years fail preferentially at the first sustained winter workload — the seasonal pattern behind many an E28.
When to call a Gas Safe engineer
Past the power check, flue-terminal glance and one listening reset, E28 is Gas Safe engineer work — fan, switch and flue all live behind the case, guarded by an interlock that means what it says. On this platform the fix is famously quick: universal parts, total engineer familiarity, single-visit norms. Report the start-up sound when booking; silence, labouring and healthy-then-lockout each point at a different link in the chain.
Carbon monoxide is odourless and colourless. Our CO safety guide covers the symptoms, where alarms belong and the emergency response.
Frequently asked questions
What does E28 mean on a Baxi boiler?
Fan fault: the fan didn't run or didn't prove the airflow required before ignition, so the boiler is refusing to light. The refusal is the safety interlock doing its job.
Can I run the boiler while waiting for the engineer?
No — and it won't let you, by design. Repeated resets against a fan code force attempts against an unproven flue path; one listening reset for diagnosis, then book.
Is E28 the same on Potterton boilers?
Yes — shared platform, shared code, same meaning and causes, and the same cheap ubiquitous parts once diagnosed. Engineers move between the badges without a pause.
How much does a Baxi fan fault cost to fix?
Typically a mid-priced part plus short labour — the platform's serviceability and parts pipeline keep it economical, and it rarely changes the repair-or-replace picture on a boiler with years left.
Is a boiler fan expensive to replace?
It's a mid-priced component — meaningful but rarely a repair-or-replace trigger on its own for a boiler with life left. Diagnosis is quick for an engineer, and the part is stocked for all mainstream brands.
The fan runs but the boiler still locks out — why?
Running isn't enough; the air pressure switch must see the right airflow. A tired fan below spec, a partially blocked flue, or a faulty switch all produce that exact symptom, and distinguishing them is instrument work behind the case.
If you'd rather hand this over
Plenty of readers reach this point, weigh the afternoon involved, and sensibly hand it to someone who does it weekly. No judgement — that's what the network exists for. Every engineer is Gas Safe registered (plus OFTEC for oil and MCS for heat pumps), insured and locally based; prices are agreed up front; and genuine no-heat emergencies are prioritised. Describe the symptoms you've identified here and you'll get an accurate price rather than a guess — informed customers reliably get better quotes.