Keston E67 Fault Code: Causes, Fixes & Repair Costs
What does the Keston E67 fault code mean?
The E67 code appears on Keston Qudos boilers when the system water pressure drops below 0.4 bar — the minimum threshold the boiler needs to operate safely. At this point the boiler locks out completely and will not restart on its own; you must resolve the pressure issue and then press the reset button to get it running again. Normal working pressure for a Keston system should sit between 1.0 and 1.5 bar, with around 1.2–1.3 bar being ideal. E67 is essentially the boiler's way of telling you there is not enough water in the sealed system to circulate safely.
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
- Pressure has dropped but there is no active leak Common
Over months or years, sealed heating systems naturally lose small amounts of pressure through micro-permeation and occasional bleeding of radiators. If the pressure has simply drifted down below 0.4 bar but is not actively falling, a one-off repressurise via the filling loop is usually all that is needed.
- Leak somewhere in the heating system Common
If the pressure keeps dropping after you top it up — for example falling noticeably within days or weeks — water is escaping somewhere. Common leak points include radiator valves, pipe joints behind walls or under floors, and the boiler's internal connections. Water may not always be visible; it can soak into plasterwork or floorboards before becoming obvious.
- Faulty or waterlogged expansion vessel Sometimes
The expansion vessel contains a rubber diaphragm that absorbs pressure changes as the system heats and cools. If the diaphragm perishes or the nitrogen charge is lost, the vessel can no longer do its job. This often causes the pressure gauge to swing wildly between cold and hot, and can lead to the pressure relief valve repeatedly dumping water — which itself causes the pressure to drop and trigger E67.
- Pressure relief valve (PRV) weeping or failing open Sometimes
The PRV is a safety device designed to release water if pressure climbs too high. A PRV that is worn or has been subjected to repeated overpressure events can start to weep continuously, slowly bleeding the system down below the 0.4 bar threshold. You may notice a small pipe outside the property (the PRV discharge pipe) dripping or running water.
How to fix it
- Check the pressure gauge on the boiler DIY safe
Look at the pressure gauge — either a dial or a digital display. If it reads below 1.0 bar (or is showing near zero), low pressure is confirmed as the cause of E67. If the gauge reads above 1.0 bar, the fault may have a different underlying cause and you should contact an engineer.
- Top up the system pressure using the filling loop DIY safe
Switch the boiler off and let it cool for at least 30 minutes — ideally an hour — before repressurising. Locate the filling loop, which is usually a braided flexible hose with two valves situated beneath the boiler. Slowly open both valves and watch the pressure gauge rise. Stop when it reaches approximately 1.2 bar (do not exceed 1.5 bar). Close both valves firmly, then disconnect and store the filling loop. If your Keston boiler has an integral (built-in) filling loop, follow the same principle using the designated valves.
- Reset the boiler DIY safe
Press and hold the reset button on the boiler's control panel until the boiler attempts to fire. E67 will not clear automatically — the reset must be performed manually after the pressure has been restored. If the boiler does not restart after one or two reset attempts, do not continue pressing reset repeatedly.
- Monitor the pressure over the following days DIY safe
Check the pressure gauge every day or two. If it holds steady around 1.0–1.5 bar and E67 does not return, the issue was a simple pressure drop and no further action is needed. If pressure falls again within days or weeks, there is an underlying problem — a leak, a faulty expansion vessel, or a weeping PRV — that needs professional attention.
- Check the PRV discharge pipe for dripping water DIY safe
Find the small-diameter pipe that exits the boiler and terminates outside (often through an external wall, low down). If water is trickling or dripping from it, the PRV is releasing pressure — this suggests either the PRV itself is faulty or the expansion vessel is no longer absorbing pressure fluctuations correctly. Make a note of this to tell your engineer.
- Call a Gas Safe registered heating engineer Gas Safe engineer
If pressure keeps dropping, if you cannot locate the filling loop, if the PRV discharge pipe is dripping, or if the boiler fails to stay running after a reset, contact a Gas Safe registered engineer. They will carry out a leak detection check, test the expansion vessel charge and replace it if needed, and assess the PRV. Do not attempt to open sealed system components, adjust the PRV, or carry out any internal boiler work yourself.
Parts you may need
- Expansion vessel (replacement) · from £80
- Expansion vessel Schrader valve / recharge kit · from £15
- Pressure relief valve (PRV) · from £25
- Filling loop assembly · from £20
- Pressure gauge · from £18
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 £100–£350, depending on the underlying cause.
Frequently asked questions
Can I repressurise my Keston boiler myself to clear E67?
Yes — topping up the system pressure via the filling loop is a straightforward homeowner task. Switch the boiler off, let it cool, then slowly open the filling loop valves until the gauge reads around 1.2 bar. Close the valves, then press reset. If the pressure holds and E67 does not return, you are done. However, if you cannot find the filling loop, if the pressure drops again quickly, or if you are unsure at any stage, call a Gas Safe engineer rather than guessing.
Why does my Keston boiler keep losing pressure and showing E67 again?
Recurring pressure loss after repressurising points to an underlying fault rather than a simple top-up issue. The most common culprits are a small leak somewhere in the pipework or radiator valves, a waterlogged expansion vessel that can no longer absorb pressure changes, or a pressure relief valve (PRV) that has started to weep. A Gas Safe engineer can carry out a leak detection check and test the expansion vessel charge to pinpoint the cause. Repeatedly topping up without fixing the root cause risks water damage to your property and boiler internals.
How much does it cost to fix a Keston E67 fault in the UK?
If the boiler simply needed repressurising, an engineer call-out for that alone typically costs £60–£100. A PRV replacement usually comes in around £100–£150 including labour. Expansion vessel replacement — the most common repair behind recurring E67 faults — typically costs £150–£350 all in, depending on the vessel size and access. If the expansion vessel and PRV both need replacing at the same time (which engineers often recommend when one has failed), expect to pay toward the upper end of that range. Leak repairs vary considerably depending on where the leak is located.
What pressure should my Keston boiler run at?
Keston recommends a cold system pressure of around 1.0 to 1.5 bar, with 1.2–1.3 bar being a good target when the system is cold. When the heating is running and the water is hot, pressure will naturally rise slightly — typically to around 1.5–2.0 bar — which is normal. If you see the pressure climbing above 2.5 bar or the PRV discharge pipe running with water, that suggests a different problem (often a failed expansion vessel) and you should call an engineer promptly.