Baxi E111 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E111 fault code mean?
The E111 fault code on a Baxi boiler indicates that the fan is not running at the expected speed. The fan is a critical component — it draws in combustion air and expels exhaust gases through the flue. When the boiler's control system detects that the fan speed is outside the acceptable range (either too slow, too fast, or not turning at all), it locks the boiler out as a precaution. This prevents unsafe combustion conditions and potential flue gas spillage. The boiler will not fire until the fault is investigated and resolved.
General guidance only — not a substitute for professional advice. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Worn or failed fan motor Common
Over time the fan motor bearings wear out, causing the fan to spin erratically or stop altogether. This is the single most common cause of E111 on Baxi boilers. You may notice an unusual whirring, grinding, or humming sound just before the lockout occurs.
- Faulty fan wiring or connector Common
The wiring harness running to the fan, or the plug-in connector at the fan itself, can work loose, corrode, or develop a break. This gives the PCB an incorrect or absent speed signal, triggering E111 even if the fan motor itself is still functional.
- Faulty PCB or fan control circuit Sometimes
The printed circuit board (PCB) monitors fan speed via a tachometer signal. If the PCB develops a fault on the fan-monitoring circuit, it may incorrectly report an E111 even when the fan is operating normally. This is less common but worth investigating if the fan and wiring check out fine.
- Blocked or restricted flue Sometimes
A partial blockage in the flue — from a bird's nest, debris, or ice in very cold weather — can place extra resistance on the fan, causing it to run outside its expected speed range and trip the fault.
How to fix it
- Reset the boiler once DIY safe
Press and hold the reset button (usually marked with a flame or 'R' symbol) for around 3 seconds, then release. Allow the boiler a full minute to attempt a restart. A single reset is worthwhile in case E111 was triggered by a momentary voltage fluctuation. Do not reset more than 2–3 times in total — repeated resets without fixing the underlying problem can cause further damage.
- Check your gas supply DIY safe
Confirm that other gas appliances in your home (hob, gas fire) are working normally. If there is no gas anywhere, contact your gas supplier or call the National Gas Emergency Line on 0800 111 999. If the fan fault returns after resetting, gas supply is unlikely to be the cause, but it is a quick check worth making.
- Inspect the flue terminal externally DIY safe
From outside, take a visual look at the flue outlet (usually on an external wall or roof). Check for obvious obstructions such as a bird's nest, leaves, or ice build-up. Do not attempt to probe or dismantle any part of the flue yourself. If you can see a clear blockage at the terminal, report this to your engineer when you call.
- Listen for unusual fan noises DIY safe
When the boiler attempts to start (after a reset), listen carefully for grinding, rattling, or a high-pitched whine from the boiler casing. This can help your engineer diagnose whether the fault is mechanical (motor/bearings) or electrical (wiring/PCB) before they arrive.
- Call a Gas Safe registered engineer Gas Safe engineer
All internal fan work — removing the fan assembly, testing the motor, checking the tachometer wiring, and inspecting or replacing the PCB — must be carried out by a Gas Safe registered engineer. The engineer will test fan speed, check the wiring harness and connectors, and replace whichever component has failed. Most visits for this fault take between 40 and 90 minutes depending on parts availability and boiler access.
Parts you may need
- Baxi boiler fan assembly · from £160
- Fan wiring harness / connector · from £25
- PCB (printed circuit board) · from £220
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £220–£420, depending on the underlying cause.
Frequently asked questions
Can I fix a Baxi E111 fault myself?
No. Although you can safely reset the boiler and carry out a few basic checks (gas supply, visual flue inspection), the fan is an integral part of the combustion and exhaust system. Working on it without Gas Safe registration is both illegal and dangerous. Always call a registered engineer for anything beyond a reset.
How much does it cost to fix a Baxi E111 fault in the UK?
For most homeowners the repair comes to between £220 and £420 including parts and labour. A straightforward fan motor replacement typically sits toward the lower end of that range. If the PCB also needs replacing the bill can climb higher — sometimes £400–£600 or more — but that scenario is less common. Ask your engineer to diagnose the root cause before agreeing to any parts replacement.
Will resetting the boiler fix E111?
Occasionally a single reset clears a spurious E111 caused by a brief electrical glitch, and the boiler runs normally afterwards. However, if the code returns after resetting, the underlying fault (worn fan motor, broken wiring, or a PCB issue) is still present. Repeatedly resetting without a repair risks damaging other components, so limit resets to two or three at most and then call an engineer.
How long does a Baxi fan replacement take?
Most Gas Safe engineers complete a fan replacement on a Baxi boiler within 40 to 90 minutes, provided they have the correct part with them. It is worth asking when you book whether the engineer carries common Baxi fan assemblies in their van, as this avoids a return visit for parts.