Buderus 9H 272 Fault Code: Causes, Fixes & Repair Costs
What does the Buderus 9H 272 fault code mean?
The 9H 272 code is a lockout fault on Buderus boilers, meaning the appliance has shut down and will not restart until manually reset. It is built from two parts: the '9' indicates a system-level fault category, the 'H' (displayed flashing) signals a lockout condition, and the subcode '272' points specifically to a fault detected by the UBA — Buderus's Universal Burner Automatic, the proprietary control board that manages the entire burner sequence. Subcode 272 is associated with a faulty or unreliable cable connection between the UBA and the gas burner assembly. Related subcodes in the same fault family include 267 (also a UBA fault) and 237 (UBA communication fault); if your display shows any of these alongside '9H', the diagnosis and repair pathway are broadly the same. In plain terms: the boiler's brain has detected a problem with the wiring or electronics controlling the burner, and has locked out as a safety measure.
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
- Loose or disconnected cable to the gas burner assembly Common
The most frequently identified cause for subcode 272. The wiring loom connecting the UBA to the gas burner assembly can work loose over time due to vibration or thermal cycling. A poor contact at the plug is often enough to trigger a lockout. Re-seating or replacing the connector commonly resolves the fault.
- Corroded or damaged connector pins on the UBA Common
The multi-pin plug that attaches to the UBA can suffer from corrosion or bent pins, preventing a reliable electrical connection. Even a single compromised pin can cause the UBA to register a burner wiring fault. This is frequently found on older appliances or in boilers installed in damp plant rooms.
- Blown UBA fuse Sometimes
A small ceramic fuse (typically 5 A, 250 V fast-blow) on or associated with the UBA can fail following a power surge or short circuit. If the fuse has blown, the UBA loses part of its control circuit and triggers a lockout. Checking and replacing this fuse is a straightforward engineer task.
- Failed or damaged UBA (main control board) Sometimes
If all wiring connections and the fuse are found to be intact, the UBA itself may have suffered an internal failure — from a failed component, moisture ingress from an internal leak, or age-related degradation. A failed UBA typically requires replacement and is one of the more expensive outcomes for this fault code.
- KIM (Communication Interface Module) connection fault Rare
The KIM module handles communication between the UBA and external controls. A loose or faulty connection between the UBA and the KIM can generate a system fault in the same category. An engineer should check this connection if the primary wiring and UBA checks draw a blank.
How to fix it
- Attempt a single boiler reset DIY safe
Locate the Reset button on the boiler's control panel and press it once. Allow the boiler a full minute to attempt a restart. If the 9H 272 code returns immediately or within a short time, do not reset more than two or three times in total — repeated resets on a lockout fault can damage the ignition transformer and will not cure an underlying wiring or board fault.
- Check your gas supply is on DIY safe
Confirm that the gas isolation valve on the supply pipe to the boiler is in the open (in-line) position and that other gas appliances in the property are working normally. If your gas supply has been interrupted, contact your gas supplier before resetting the boiler again.
- Call a Gas Safe registered engineer to inspect wiring to the gas burner assembly Gas Safe engineer
An engineer should carefully remove the UBA module — by releasing its retaining screw — and inspect the multi-pin connector and cable loom running to the gas burner assembly. They should check for loose contacts, bent or corroded pins, and any visible wiring damage. Sometimes disconnecting and firmly re-seating the plug is sufficient to restore the connection; a damaged loom will need replacing.
- Engineer to check and test the UBA fuse Gas Safe engineer
The engineer should locate the fuse associated with the UBA circuit, remove it from the fuse holder, and test continuity with a multimeter. If the fuse has blown, it must be replaced like-for-like with a ceramic fast-blow fuse of the correct rating (typically F5AH, 250 V) before retesting.
- Engineer to check the KIM module and its connections Gas Safe engineer
If the burner wiring and fuse are both in order, the engineer should inspect the connections between the UBA and the KIM (Communication Interface Module). A fault in this communication path can generate a 9-category lockout and may be misidentified as a pure UBA failure.
- Replace the cable loom or UBA if fault persists Gas Safe engineer
Where all connections check out but the fault code continues to appear after reset, the engineer will need to determine whether the cable harness itself has failed internally or whether the UBA board has suffered an irreparable fault. A new cable loom or a replacement UBA — ordered from Buderus or an authorised parts supplier — will be required. After fitting, the engineer should reconnect all plug-in cables carefully, verifying each socket, and perform a full function test.
- Contact a Gas Safe registered engineer if you have not already done so Gas Safe engineer
Because 9H 272 involves the burner control system and gas-related wiring, no part of the diagnosis or repair beyond the initial reset is safe for a homeowner to carry out. Always provide the engineer with the exact code shown on the display (9H 272) and your boiler's full model designation so they can prepare the correct parts before attending.
Parts you may need
- Buderus UBA (Universal Burner Automatic) control board · from £320
- Burner assembly cable loom / wiring harness · from £75
- UBA multi-pin connector plug · from £25
- Ceramic fast-blow fuse F5AH 250V (pack) · from £5
- KIM communication interface module · from £110
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–£400, depending on the underlying cause.
Frequently asked questions
Can I fix Buderus 9H 272 myself by resetting the boiler?
You can try a reset once or twice — that is the only homeowner action available for this lockout code. However, 9H 272 points to a fault inside the burner control wiring or the UBA board itself, and no amount of resetting will cure a loose connector, a blown fuse, or a failed PCB. If the code returns after one or two resets, you need a Gas Safe registered engineer to investigate.
What is the difference between subcodes 272, 267, and 237 on a Buderus 9H fault?
All three are sub-codes within the category 9 system fault group. Subcode 237 typically indicates a communication fault between the UBA and the KIM module. Subcodes 267 and 272 both point to a UBA fault, with 272 specifically associated with a faulty cable connection to the gas burner assembly. In practice an engineer will check the wiring, connectors, and the UBA board for all three codes — the repair pathway is very similar.
How much does it cost to replace a Buderus UBA control board in the UK?
If a simple wiring fix or fuse replacement resolves the fault, total costs including the engineer's callout and labour are typically £120–£250. If the UBA board itself needs replacing, parts alone are usually £280–£380 for a Buderus UBA, and with two to three hours of diagnostic and fitting labour you should budget roughly £400–£650 in total. If your boiler is over 15 years old, it is worth comparing that figure against the cost of a new appliance before committing to a board replacement.
Is it safe to keep using my boiler after a 9H 272 lockout?
No — the boiler has locked out precisely because it has detected a fault in the burner control circuit. It will not fire while the code is active, so you have no heating or hot water. You should not attempt to override the lockout or repeatedly reset the boiler hoping it clears on its own. Arrange for a Gas Safe registered engineer to attend as soon as possible, particularly during colder months.