Buderus 9H 267 Fault Code: Causes, Fixes & Repair Costs
What does the Buderus 9H 267 fault code mean?
The Buderus fault display works on a two-code system: the primary code shown on screen is 9H, and pressing the Service button reveals the secondary sub-code 267. Together they tell you the boiler's UBA (Universal Burner Adaptor) — Buderus's term for the main control board — has detected an internal system fault and shut the boiler down. The '9' group covers UBA-related system errors, the 'H' prefix confirms this is a locking fault (meaning the boiler will not restart on its own and needs a manual reset after the problem is resolved), and 267 pinpoints the specific error within that group. The UBA is the electronic brain of the boiler: every signal from the thermostat, pressure sensor, and safety switches feeds into it, and it then issues instructions to the pump, fan, and gas valve to maintain safe and efficient combustion. When the UBA detects something it cannot reconcile internally — whether a genuine board failure, a wiring issue, a blown fuse, or moisture damage — it raises this locking fault and stands the boiler down until an engineer investigates.
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
- Faulty or failed UBA control board Common
The UBA PCB itself may have developed an internal fault — a failed component, a cracked solder joint, or general wear. This is the most direct cause of a 9H 267 code and typically requires board replacement by a Gas Safe registered engineer familiar with Buderus systems.
- Loose or poor wiring connections within the UBA Common
Connectors and pin headers on the UBA can work loose over time due to vibration and thermal cycling. A poor connection can cause the board to log a system error even when the hardware is otherwise sound. Re-seating or remaking a connector sometimes clears the fault without any further work.
- Blown internal UBA fuse Sometimes
The UBA contains an internal ceramic fuse (typically rated 5 A, 250 V fast-blow). If this fuse has blown — often due to a transient electrical spike — the board will report a system fault. Checking and replacing this fuse is a straightforward task for an engineer but should not be attempted by a homeowner.
- Moisture or water ingress onto the board Sometimes
A dripping pump seal, a weeping heat exchanger, or condensate accumulation can allow water to reach the UBA. Even small amounts of moisture can cause tracking or short circuits on the board, producing this fault code. If corrosion or water staining is visible on the board or nearby wiring, the source of the leak must be found and fixed before the board is replaced.
- Communication failure between UBA and KIM module Rare
The UBA communicates with other control modules in the system, including the KIM interface. A disruption in that communication — caused by a damaged data cable, a connector fault, or a software glitch — can trigger a UBA system error in the 9H fault group, with sub-codes in the 237–267 range flagging this type of inter-module issue.
How to fix it
- Reset the boiler once — but no more than twice or three times total DIY safe
Press the reset button on the boiler control panel. The display will briefly show 'r' to confirm the UBA has been unblocked and returned to standby. If the boiler fires up and runs normally, monitor it over the next few hours. Important: do not keep pressing reset if the fault returns immediately — repeatedly forcing the ignition sequence when a board fault is present can damage the ignition transformer. Limit yourself to two or three attempts in total.
- Check that your gas supply is working DIY safe
Confirm that other gas appliances in your home (hob, gas fire) are working normally. If they are not, contact your gas supplier rather than continuing to reset the boiler. If the gas supply is fine, the fault is internal to the boiler and an engineer is needed.
- Inspect around the boiler for any visible water leaks DIY safe
Look around the base of the boiler, along pipework, and at the pump casing for any signs of dripping or damp. Do not touch internal components, but if you can see an active leak near the boiler electronics, turn the boiler off at the main switch and call an engineer promptly — moisture near the UBA will cause further damage if left.
- Check system pressure and top up if low DIY safe
Look at the pressure gauge on the boiler. Normal operating pressure for most Buderus combi and system boilers is between 1.0 and 1.5 bar when cold. If it reads below 1.0 bar, top up via the filling loop following the guidance in your boiler's user manual. A 9H 267 fault is not typically caused by low pressure alone, but eliminating this variable is a sensible first step before calling an engineer.
- Engineer to inspect UBA connections and re-seat the board Gas Safe engineer
A Gas Safe registered engineer will remove the boiler casing and carefully extract the UBA module (usually secured by a centre screw). They will inspect all pin connectors and wiring harnesses for signs of looseness, corrosion, or damage, re-seat the board correctly, and retest. This alone resolves a proportion of 9H 267 faults without needing new parts.
- Engineer to test the internal UBA fuse Gas Safe engineer
The engineer will dismantle the UBA fuse holder using the bayonet release and use a multimeter to test continuity through the fuse. If continuity is absent, the fuse has blown and will be replaced with the correct ceramic fast-blow type (5 A, 250 V — F5AH 250V). The board is then retested before the boiler is recommissioned.
- Engineer to check for moisture ingress and repair any leaks Gas Safe engineer
If the board or surrounding wiring shows signs of water damage — corrosion, staining, or tracking marks — the engineer must trace and fix the source of moisture before fitting any replacement parts. Fitting a new UBA into a boiler that is still leaking will simply damage the replacement board.
- Engineer to replace the UBA/PCB if the fault persists Gas Safe engineer
If re-seating, fuse replacement, and wiring checks have not resolved the fault, the UBA board itself is defective and needs replacing. Buderus UBA modules are specialist parts that often need to be ordered directly through Buderus or an approved supplier. The engineer will fit the replacement, configure it correctly for your boiler model, and carry out a full functional test before signing off the work.
- Call a Gas Safe registered engineer if you have not already done so Gas Safe engineer
A 9H 267 fault is a control board lockout that requires hands-on investigation by a qualified professional. If the boiler has not responded to a reset, or the fault has returned more than once, book a Gas Safe registered engineer — ideally one with Buderus or Worcester Bosch Group experience — as soon as possible, particularly if you have no heating or hot water in cold weather.
Parts you may need
- Buderus UBA 3 / UBA 4 Control Board (model-specific) · from £280
- Internal UBA ceramic fuse (F5AH 250V fast-blow) · from £5
- UBA wiring harness / connector set · from £45
- Boiler pump (if moisture ingress source) · from £90
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 £150–£550, depending on the underlying cause.
Frequently asked questions
Can I fix a Buderus 9H 267 fault myself?
Only in the most limited sense. As a homeowner you can safely reset the boiler (up to two or three times), check that your gas supply is on, top up system pressure if it is low, and look for obvious water leaks near the boiler. Everything beyond that — opening the boiler casing, handling the UBA board, testing fuses, or replacing components — must be done by a Gas Safe registered engineer. The UBA is the boiler's main control board, and working on it without the proper qualifications is both unsafe and illegal.
How much does it cost to fix a Buderus 9H 267 fault in the UK?
If the fault turns out to be nothing more than a loose connector or a blown internal fuse, most engineers can sort it in a single visit — expect to pay roughly £150 to £250 including call-out and labour. If the UBA board itself needs replacing, the cost rises considerably: the part alone typically costs £250 to £350 for a Buderus-compatible UBA module, and with labour the total often falls between £400 and £550. In some regions or with urgent callouts, costs can be higher. If your boiler is more than ten years old, it is worth asking your engineer whether a new boiler would be a better investment than a PCB replacement.
What is the difference between the 9H display code and the 267 sub-code on my Buderus boiler?
Buderus boilers use a two-part fault display. The primary code — 9H in this case — appears on screen automatically when a fault occurs. The '9' indicates a UBA system fault group, and the 'H' confirms it is a locking fault, meaning the boiler will not restart without a manual reset. To see the sub-code, you press the Service button, which then shows 267. This sub-code narrows down the specific nature of the UBA fault for the engineer. Other sub-codes in the same group (such as 237) point to related UBA system errors, so if your display shows 9H with a different sub-code, the diagnostic approach is broadly similar but your engineer will use the exact sub-code to guide their checks.
My Buderus boiler keeps coming back with the 9H 267 fault after I reset it — what should I do?
A fault that returns repeatedly after reset is telling you the underlying problem has not gone away. Stop resetting the boiler — pressing reset more than two or three times in succession when a board fault is present can damage the ignition transformer. Instead, check for any visible water leaks around the boiler (moisture is a common cause of UBA failures), then call a Gas Safe registered engineer. A recurring 9H 267 usually means the UBA board has an intermittent or permanent fault, a wiring connection has deteriorated, or there is an ongoing source of moisture affecting the electronics — none of which a reset can fix.