Keston E10 Fault Code: PCB / Control Board Error
The E10 code on a Keston boiler signals that the control board (PCB) has detected an internal error and cannot operate normally. When this code appears, the boiler enters a lockout state and shuts down completely — it will not restart on its own. You must press the boiler's dedicated reset button to attempt a restart once the underlying issue has been addressed; simply switching the power off and back on will not clear the lockout.
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.
What does the Keston E10 fault code mean?
The E10 code on a Keston boiler signals that the control board (PCB) has detected an internal error and cannot operate normally. When this code appears, the boiler enters a lockout state and shuts down completely — it will not restart on its own. You must press the boiler's dedicated reset button to attempt a restart once the underlying issue has been addressed; simply switching the power off and back on will not clear the lockout.
Common causes
- Faulty or failed PCB Common
The control board itself has developed an internal fault — either losing its stored settings or experiencing a component failure on the board. This is the most direct cause of E10 and typically requires a Gas Safe engineer to diagnose using a multimeter before a replacement PCB can be considered.
- Moisture or internal leak damaging the PCB Common
Water ingress is one of the most common ways a PCB fails prematurely. If the boiler has an internal leak — even a slow drip — moisture can track along wiring and find its way onto the circuit board, causing short circuits or corrosion. The leak must be identified and repaired before any new PCB is fitted, otherwise the replacement board is at risk of the same damage.
- Loose or corroded wiring connections Sometimes
A loose or degraded wire connector — particularly on circuits running to the fan or gas valve — can send corrupt signals that the PCB interprets as an internal error. Engineers will check all harness connections before condemning the board itself.
- Power surge or mains voltage irregularity Sometimes
A sudden spike in mains voltage can overwhelm the sensitive electronics on the control board. Early signs may include a flickering display or unexpected shutdowns before the fault becomes permanent. A surge protector on the boiler's mains supply can help prevent recurrence after a repair.
- Separate underlying fault triggering a PCB shutdown Rare
Occasionally another boiler fault — such as an ignition failure or fan issue — places abnormal demand on the PCB and causes it to shut itself down as a protective measure. Clearing the root cause may resolve the E10 without any work on the board itself.
How to fix it
- Switch the boiler off at the mains, wait 30 seconds, then switch it back on and press the reset button DIY safe
A brief power cycle can clear minor transient electronic errors. If the boiler fires up and runs normally, monitor it closely over the next 24 hours. If E10 returns, do not keep resetting — repeated lockouts on the same fault indicate a genuine problem that needs professional attention. Limit resets to no more than two or three attempts total.
- Check for visible signs of a water leak around the boiler DIY safe
Look carefully around the base of the boiler, beneath pipe connections, and around the heat exchanger area for any damp patches, drip marks, or corrosion staining. If you spot a leak, do not attempt to repair it yourself — note its location and report it to the engineer, as fixing the leak before replacing the PCB is essential.
- Verify the boiler's system pressure is within range DIY safe
Check the pressure gauge on the front of the boiler. It should read between 1.0 and 1.5 bar when the system is cold. If it has dropped below 0.8 bar, top it up via the filling loop following your boiler's user guide. Very low pressure can sometimes contribute to unusual control board behaviour, though it is rarely the sole cause of E10.
- Contact a Gas Safe registered engineer with Keston experience Gas Safe engineer
Keston boilers use a twin-flue design and a modulating pump that not all engineers are familiar with. When booking, ask specifically whether the engineer has worked on Keston appliances before. If in doubt, use the engineer finder at keston.co.uk or contact the Keston technical helpline (Keston is part of the Ideal group) for a recommended local engineer.
- Engineer to diagnose the PCB and inspect all wiring harnesses Gas Safe engineer
The engineer will use a multimeter to confirm whether the board is receiving correct voltage and sending proper signals. They will also inspect all wiring connectors — particularly those running to the fan and gas valve — for signs of corrosion, burning, or loose pins. This step determines whether the board needs replacing or whether a wiring fix is sufficient.
- Engineer to check for and repair any internal leaks before replacing the PCB Gas Safe engineer
If any leak is found inside the boiler, it must be fully repaired and the affected area dried out before a new control board is installed. Fitting a replacement PCB into a boiler with an active leak is a false economy — the new board is likely to suffer the same water damage within a short time.
- Engineer to replace the PCB if confirmed faulty Gas Safe engineer
If the board is confirmed defective and no other repairable cause is found, the engineer will source a replacement Keston PCB — note that this part is highly specialised and is unlikely to be on the van, so expect a lead time while the part is ordered, typically from Keston or an Ideal group distributor. Fitting and testing the new board usually takes one to three hours.
Parts you may need
- Keston PCB / control board · from £280
- Wiring harness · from £45
- Ignition lead · from £30
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 £380–£650, depending on the underlying cause.
Frequently asked questions
Can I fix Keston E10 myself by resetting the boiler?
You can try a single reset — switch off at the mains, wait 30 seconds, turn back on and press the reset button. If the boiler runs normally afterwards, keep an eye on it. However, if E10 returns or the boiler won't stay running, repeated resets won't help and a Gas Safe engineer is needed. The PCB itself is not a DIY repair under any circumstances.
How much does it cost to replace a Keston boiler PCB in the UK?
Most homeowners pay between £380 and £650 all-in for PCB diagnosis, the replacement part, and labour in 2025. The board itself is a specialist component that engineers usually have to order directly, which can add a few days to the process. If the boiler also has an internal leak that caused the PCB to fail, fixing that will add to the overall bill. In cases where the boiler is over 10 years old, it's worth getting a new boiler quote alongside the repair quote, as a modern A-rated boiler may offer better long-term value.
Why is Keston E10 more complex to repair than on other boilers?
Keston boilers use a twin-flue system and a modulating pump that differ significantly from the more common combi boiler designs. Not every engineer is familiar with the setup, which can make diagnosis slower and parts harder to source quickly. Always ask a prospective engineer whether they have hands-on Keston experience before booking — or use the engineer search on keston.co.uk to find someone recommended by the manufacturer.
Could something other than the PCB be causing E10?
Yes. While E10 directly flags a control board error, the PCB is sometimes reacting to another problem rather than failing on its own. Internal water leaks, loose wiring connectors, or a separate component fault (such as a fan issue) can all stress the board and trigger a shutdown. A good engineer will investigate the full picture before recommending a PCB replacement, because fitting a new board without fixing the root cause often leads to the same fault returning.