Worcester Bosch F0 262 Fault Code: Causes, Fixes & Repair Costs
What does the Worcester Bosch F0 262 fault code mean?
The F0 262 fault code is a locking error, meaning your Worcester Bosch boiler has shut itself down completely and will not restart without a manual reset. The F0 prefix indicates an internal burner control fault, and the 262 sub-code places this firmly within the F0 2xx range, which points to a problem with the burner control unit (known as the KIM — Kessel Identifikations Modul) or associated wiring and electronics. In plain terms, the boiler's internal control system has detected something it cannot safely ignore and has locked out as a precaution. You will typically see a flashing fault code on the display alongside a triangle warning symbol. Related sub-codes in this family include F0 238, F0 242–253, and F0 259–272, all of which share the same KIM/BCU fault category — so if your display shows any F0 2xx code, the diagnosis and checks described here apply.
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 burner control unit (KIM) Common
The KIM is the dedicated module that manages burner operation and safety sequences. When it develops an internal fault or its plug and wiring connections become loose, corroded, or damaged, the boiler logs an F0 2xx code and locks out. This is the most direct cause indicated by the 262 sub-code.
- PCB failure or damage Common
The main printed circuit board orchestrates every function in the boiler. A power surge, component ageing, or moisture ingress can cause the PCB to report internal errors that surface as F0 faults. The boiler's fault LED and reset button will typically be flashing when this is the culprit.
- Wiring fault or poor connection Sometimes
Damaged, pinched, or poorly seated wiring between the KIM, PCB, and other components can interrupt communication and trigger this lockout. Vibration over time or rodent damage to cables are typical causes.
- Gas valve fault Sometimes
A faulty modulating gas valve or its relay can cause burner control errors that are reported under the F0 family. The valve may be failing to open, closing unexpectedly, or sending incorrect feedback signals to the control board.
- Power surge or electrical interruption Rare
A recent power cut or voltage spike can corrupt the boiler's internal electronics or trigger a spurious lockout. If the fault clears after a single reset and does not return, a transient electrical event may have been the cause.
How to fix it
- Note down exactly what the display shows and record any recent events DIY safe
Before touching anything, write down the full code as displayed (e.g. F0 262), note whether heating, hot water, or both have stopped, and recall whether there was a recent power cut or surge. This information is genuinely useful to the engineer and helps them diagnose the fault faster.
- Check that other gas appliances in your home are working DIY safe
Turn on a gas hob ring or check another gas appliance. If nothing gas-powered is working, the issue may be with your gas supply rather than the boiler itself. If you have no gas, contact your gas supplier. Do not attempt to investigate the boiler further until you have confirmed the supply is active.
- Check your boiler's system pressure DIY safe
Look at the pressure gauge on the boiler (usually on the front panel). It should read between 1.0 and 1.5 bar when cold. If it is below 1 bar, top it up using the filling loop — usually a braided flexible hose or a built-in lever beneath the boiler. Consult your boiler's user guide for the exact filling loop location on your model.
- Attempt a boiler reset — no more than twice DIY safe
Press and hold the reset button for approximately three seconds, then release. If the boiler fires up and runs normally, monitor it over the next few hours. If it locks out again, press and hold the reset button for around 10 seconds, wait 30 seconds, then try once more. Do not reset more than twice — repeated resets on a genuine internal fault can mask the problem and make diagnosis harder.
- Stop resetting and call a Gas Safe registered engineer if the fault returns Gas Safe engineer
A recurring F0 262 fault almost always means there is an underlying component issue — most likely with the KIM, PCB, wiring, or gas valve. At this point, further resets will not resolve the problem. A qualified Gas Safe engineer must carry out the internal diagnosis, which involves checking the KIM module and its wiring harness, testing or replacing the PCB, and inspecting the gas valve and burner assembly. Do not open the boiler casing or attempt to inspect wiring yourself.
Parts you may need
- Burner control unit (KIM / BCU) · from £180
- Main PCB · from £220
- Gas valve · from £130
- Wiring harness / loom · from £45
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–£400, depending on the underlying cause.
Frequently asked questions
Is the Worcester Bosch F0 262 fault dangerous?
The boiler has locked out as a safety precaution, so it is not actively producing heat or operating in an unsafe state. However, you should not attempt to open the boiler casing or bypass the lockout. If you smell gas at any point, leave the property immediately and call the National Gas Emergency Service on 0800 111 999.
Can I fix F0 262 myself, or do I need a Gas Safe engineer?
There are a small number of checks a homeowner can safely do — confirming the gas supply is on, checking system pressure, and attempting one or two resets. However, if the fault returns, the root cause almost certainly involves the burner control unit, PCB, wiring, or gas valve. All of these require a Gas Safe registered engineer to diagnose and repair. Working on internal boiler electronics or gas components without registration is illegal and dangerous.
How much does it cost to repair a Worcester Bosch F0 262 fault?
Most people with this fault end up paying somewhere between £150 and £400, covering the engineer's callout, diagnosis, and the most commonly replaced parts (KIM unit or wiring). If the main PCB needs replacing, the total cost including labour typically rises to £300–£550. A gas valve replacement usually falls between £200 and £350 all-in. If your boiler is over 10–12 years old and the repair quote approaches or exceeds £500, it may be worth getting a boiler replacement quote for comparison.
What is the difference between F0 262 and other F0 2xx codes like F0 238 or F0 259?
All F0 2xx sub-codes belong to the same burner control unit (KIM) fault family. The precise sub-code number reflects specific internal diagnostics logged by the boiler's firmware, but from a repair perspective they are handled the same way — an engineer checks the KIM module, its wiring and plugs, and the PCB. You do not need a different repair approach for 262 versus 238 or 259; the diagnostic process is identical.