Keston E07 Fault Code: Causes, Fixes & Repair Costs
What does the Keston E07 fault code mean?
The E07 code means your Keston boiler has detected a fan failure — either the fan is not spinning at all, or it is not reaching the speed the boiler expects. Because the fan is responsible for pushing combustion gases safely out through the flue, your boiler's PCB will refuse to attempt ignition without confirmed fan operation. The boiler enters a hard lockout and will not restart automatically; you must press the Reset button once the underlying fault has been addressed. Keston's twin-flue design makes the venturi and air pathways particularly susceptible to blockages from dust and spider webs, so this code appears more frequently on Keston appliances than on single-flue boilers of comparable age.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. 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
- Blocked venturi or air intake Common
Keston's twin-flue arrangement draws air through a venturi that is particularly prone to becoming clogged with spider webs, dust, and debris. Even a partial blockage reduces airflow enough to prevent the fan from achieving the required draught, triggering E07. This is the single most common cause on Keston boilers and is why annual servicing is so important on this range.
- Loose or damaged wiring connections to the fan Common
Each Keston fan has two separate electrical connectors. If either connector works loose — through vibration over time or a previous repair — the PCB loses its signal from the fan and immediately locks out. This is the first thing a Gas Safe engineer will physically inspect and is often the simplest fix.
- Worn or seized fan motor Sometimes
The fan motor can degrade with age, causing the fan to run too slowly or not at all. A fan running below the expected speed still produces an E07 lockout because the boiler's pressure switch cannot detect a sufficient draught, even if the motor appears to be turning. A failing motor typically needs the complete fan assembly replacing.
- PCB failing to detect fan speed correctly Rare
The PCB monitors fan speed via a feedback signal. If the control board itself is malfunctioning, it may misread or fail to register a correctly spinning fan, generating a false E07. This is less common than a physical fan fault but becomes more likely on older boilers or where a previous electrical issue has stressed the board.
How to fix it
- Check that the boiler's gas supply is turned on DIY safe
Confirm the gas isolation valve on the supply pipe behind the boiler is open (handle in line with the pipe). Verify other gas appliances in the home — such as a gas hob — are working normally. If you have no gas supply elsewhere, contact your gas supplier rather than the boiler.
- Press the Reset button once to attempt a restart DIY safe
Locate the Reset button on the boiler's control panel — on most Keston models it is clearly labelled. Press and hold it for a few seconds until the boiler attempts to fire. Observe whether E07 immediately returns. You can try resetting up to two or three times in total, but do not repeatedly reset a boiler that keeps locking out, as this can indicate a serious underlying fault.
- Do not attempt to inspect or adjust the fan yourself Gas Safe engineer
The fan, venturi, air pathways, wiring harness, and associated components are all inside the boiler casing and require a Gas Safe registered engineer to access safely. Opening the boiler yourself will void any warranty and is unsafe.
- Contact a Gas Safe engineer with Keston experience Gas Safe engineer
Because Keston boilers have a specialist twin-flue design and a modulating pump, not every Gas Safe engineer will be familiar with them. When booking, ask specifically whether the engineer has worked on Keston appliances. Keston's technical helpline (via keston.co.uk) can recommend local engineers familiar with this range. The engineer will inspect both fan connectors, check the venturi for blockages, test fan motor speed, and assess the PCB signal.
- Allow the engineer to clean the venturi or replace the fan assembly as required Gas Safe engineer
If a blockage is found, the engineer will clean out the venturi and air pathways. If the motor is failing, the entire fan assembly will typically be replaced rather than repaired. On a Keston C36 the fan assembly costs around £106 in parts; on the C40 and C55 expect around £157. Labour on top brings the typical total to £250–£400 for a straightforward fan job.
- Have the PCB assessed if the fan tests as healthy Gas Safe engineer
If the fan itself is functioning correctly but E07 persists, the engineer will check whether the PCB is correctly reading the fan speed signal. A faulty PCB will need reprogramming or replacement — this is a more expensive repair and the engineer may advise weighing the cost against the boiler's age and condition.
Parts you may need
- Fan assembly (Keston C36) · from £106
- Fan assembly (Keston C40 / C55) · from £157
- PCB (control board) · from £290
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 £200–£400, depending on the underlying cause.
Frequently asked questions
Can I fix a Keston E07 fault myself?
No. While you can safely check your gas supply is on and press the Reset button once or twice, everything beyond that — inspecting the fan, cleaning the venturi, testing the wiring, or assessing the PCB — must be done by a Gas Safe registered engineer. Working on the internal components of a boiler without Gas Safe registration is illegal and dangerous.
Why does my Keston boiler keep getting E07 even after a reset?
If E07 returns immediately or after just a short period of running, the underlying fault has not been cleared. Common reasons include a persistently blocked venturi, a fan motor that is progressively failing, or a loose electrical connector that only makes intermittent contact. Repeated resets will not resolve these issues — you need a Gas Safe engineer to carry out a proper diagnosis.
Why is it important to find an engineer with Keston experience?
Keston boilers use a twin-flue system and a modulating pump that differ significantly from mainstream combi boilers. The venturi arrangement in particular sits in places that generic boiler engineers may not be familiar with. Misdiagnosis is more likely with an inexperienced engineer, potentially leading to unnecessary parts being replaced. Keston's technical helpline at keston.co.uk can point you to engineers who regularly work on this range.
My Keston boiler is over 12 years old and has an E07 fault — is it worth repairing?
A straightforward fan replacement on an otherwise sound boiler is usually worth doing, typically costing £200–£400 all in. However, if your engineer also finds the PCB needs replacing — which can add £300–£500 or more to the bill — and the boiler has not been regularly serviced, the combined repair cost may approach or exceed the value of the appliance. In that situation it is worth getting a quote for a replacement boiler alongside the repair quote before committing.