Baxi E.01-.11 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E.01-.11 fault code mean?
The Baxi E.01–.11 fault code tells you that the boiler's control system has detected the combustion fan running at an incorrect speed — either too fast, too slow, or erratically. Because the fan is responsible for drawing fresh air into the burner and safely expelling exhaust gases (including carbon monoxide) through the flue, any deviation from the expected speed triggers an immediate safety lockout. The boiler will not fire until the root cause is identified and resolved. The suffix numbers (.01 through .11) reflect the specific point in the startup or run cycle at which the fan speed error was detected, but all variants share the same underlying cause: a fan or airflow problem that must not be ignored.
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
- Faulty or worn fan motor Common
The fan motor is the single most common culprit. Over time the motor bearings wear, the windings degrade, or internal components fail, causing the fan to run outside its target speed range. The boiler's PCB compares the actual fan speed (measured via a Hall-effect sensor or tachometer signal) against the expected value and locks out when they don't match.
- External draught or wind over the flue terminal Common
Strong gusts hitting the flue outlet can create back-pressure that either slows the fan down or causes erratic speed readings. This is especially common on boilers with externally exposed flue terminals on windy elevations. The fault may appear intermittently and correlate with bad weather.
- Blocked or partially obstructed flue or air intake Common
A bird's nest, debris, ice, or accumulated condensate in the flue or air-intake pipe forces the fan to work harder than its design allows, throwing the speed out of range. Even a partial blockage can be enough to trigger the lockout repeatedly.
- Loose, damaged, or corroded wiring to the fan Sometimes
The low-voltage speed-feedback signal from the fan to the PCB is easily disrupted by a corroded connector, a chafed wire, or a loose terminal. The PCB then reads an implausible speed and shuts the boiler down. This can produce intermittent faults that appear to clear with a reset only to return.
- Seized or obstructed fan rotor Sometimes
Dust, debris, or a failed bearing can physically prevent the fan rotor from spinning freely. The motor attempts to reach its target speed but cannot, drawing excess current and triggering the fault. You may hear a humming or grinding noise before lockout.
- Faulty PCB (control board) Rare
In rarer cases the PCB itself misreads the fan speed signal due to a damaged component or firmware issue. This is usually only confirmed after the fan, wiring, and flue have all been checked and found serviceable.
How to fix it
- Check your gas supply is on DIY safe
Confirm the gas meter isolation valve is open and that other gas appliances in the property (hob, fire) are working normally. A loss of gas pressure can indirectly affect burner ignition and cause fan-related lockouts.
- Inspect the flue terminal for obvious blockages DIY safe
From outside the property, visually check the flue outlet (and air intake on room-sealed boilers) for birds' nests, leaves, ice build-up, or any other obstruction. Do not insert anything into the flue. If you see a blockage you cannot safely clear from the outside, note it for the engineer.
- Check that furniture or objects are not covering boiler air vents DIY safe
Ensure nothing is stored directly in front of or on top of the boiler. Restricted ventilation can alter the airflow balance that the fan is trying to maintain and contribute to speed errors.
- Reset the boiler once DIY safe
Press and hold the reset button (usually marked with a flame or 'R' symbol) for around 3 seconds until the boiler attempts to re-fire. Allow a full start-up cycle. If the fault clears, monitor the boiler over the next hour. Do not reset more than once or twice — repeated resets on a fan fault will not fix the underlying problem and may mask a safety issue.
- Note whether the fault is intermittent or weather-related DIY safe
If the E.01–.11 code appears mainly on windy days or clears after a reset but returns within minutes or hours, record this pattern and relay it to your engineer. Intermittent faults that correlate with wind strongly suggest a flue draught issue or a component nearing end of life.
- Arrange a visit from a Gas Safe registered engineer to diagnose and repair the fan system Gas Safe engineer
A qualified engineer will use specialist diagnostic tools to measure the live fan speed signal, check the tachometer output, inspect the motor, test the wiring harness, and examine the flue run for blockages or leaks. Depending on findings, they may clean or free the fan rotor, replace the fan motor assembly, repair wiring, or — if the PCB is implicated — replace the control board. All work on the fan, flue, gas circuit, and PCB must be carried out by a Gas Safe registered engineer.
Parts you may need
- Baxi fan motor assembly · from £85
- Fan speed sensor / Hall-effect tachometer · from £25
- Fan wiring loom / connector repair kit · from £15
- Baxi PCB (control board) · from £180
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 £120–£350, depending on the underlying cause.
Frequently asked questions
Is the Baxi E.01–.11 fault dangerous?
Because the fan removes combustion gases — including carbon monoxide — a fan fault is treated as serious by the boiler's safety system, which is why it triggers an immediate lockout. Do not attempt to bypass the lockout or force the boiler to run. Leave the boiler off and call a Gas Safe registered engineer promptly, particularly if anyone in the property has experienced headaches or nausea, which could indicate carbon monoxide exposure.
Can I fix the Baxi E.01–.11 fault myself?
There are a few safe checks you can do: confirming the gas supply is on, looking for an obvious flue blockage from outside, and attempting a single reset. Beyond that, the fan motor, its wiring, and the PCB are all components that must only be worked on by a Gas Safe registered engineer. Attempting DIY repairs on these parts is unsafe, likely to void your warranty, and potentially illegal.
Why does my Baxi keep showing E.01–.11 after I reset it?
A fault that clears briefly then returns almost always points to a failing component rather than a one-off glitch. The most likely culprits are a fan motor nearing end of life, an intermittent wiring connection, or a partially blocked flue. Repeatedly resetting will not repair any of these — you need a Gas Safe engineer to carry out a proper diagnosis.
How much does it cost to fix a Baxi E.01–.11 fan fault in the UK?
Most homeowners pay between £120 and £350 for a Gas Safe engineer to diagnose and repair this fault. A wiring repair or flue clearance sits at the lower end; a full fan motor replacement (including parts and labour) typically falls in the £200–£300 range. If the PCB has also been damaged by the fault — which is uncommon — costs can rise to £400–£500 or more. It is worth checking whether your boiler is still within its Baxi warranty period, as fan faults on serviced boilers may be covered.