Worcester Bosch F0 290 Fault Code: Causes, Fixes & Repair Costs
What does the Worcester Bosch F0 290 fault code mean?
The F0 290 fault code indicates that the boiler's internal control electronics have detected a problem with the Heat Control Module (HCM) or control box. The 'F0' part signals a general internal control-system failure, while '290' is the cause sub-code that pinpoints the HCM or control box as the source. In practice, this means the PCB or the HCM may be defective, unseated, or suffering from a wiring or connection fault. The boiler will lock out and the fault indicator LED will flash; the unit will stop providing heating and hot water until the underlying issue is resolved. This is one of the more serious fault codes on Worcester Bosch appliances because it sits at the heart of how the boiler manages every function.
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
- Defective or incorrectly seated Heat Control Module (HCM) Common
The 290 sub-code specifically points to the HCM or control box. If the HCM has worked loose from its housing, or if the connector pins between the HCM and the main PCB are not making proper contact, the boiler's control system will register the module as faulty and lock out. Re-seating or replacing the HCM is often the first thing a Gas Safe engineer will check.
- Damaged or failing PCB Common
The main printed circuit board governs everything from ignition sequencing to pump and fan control. If the PCB develops a fault — through age, component failure, or physical damage — it can generate an F0 290 code. Signs a PCB is failing include random lockouts, components not responding, or recurring fault codes that keep returning after resets.
- Loose or corroded wiring connections Sometimes
Vibration over time, or simply poor contact at a connector, can interrupt the signals between the HCM, PCB, and other components. Corroded terminals are especially common in older boilers or those installed in damp utility rooms, and they can cause intermittent F0 faults that are difficult to pin down without proper diagnostic equipment.
- Moisture or water ingress Sometimes
A slow internal leak — from a heat exchanger joint, a pump seal, or pipework fittings — can allow moisture to reach the control electronics. Condensation from the flue or a poorly sealed boiler casing can have the same effect. Moisture causes corrosion on PCB tracks and connector pins, leading to unreliable signals and ultimately triggering an F0 fault.
- Power surge or voltage spike Rare
A sudden surge on the mains supply — caused by a lightning strike nearby, a grid fault, or a large appliance switching on — can damage sensitive electronics on the PCB or HCM. If the F0 290 code appeared immediately after a power cut or outage, this is a plausible trigger worth mentioning to your engineer.
How to fix it
- Attempt a single boiler reset DIY safe
Press and hold the reset button for approximately three seconds, then release. If the fault clears and the boiler fires up normally, monitor it over the next few hours. If the F0 290 code returns, try one further reset — hold the button for around ten seconds, wait thirty seconds, then attempt once more. Do not keep resetting beyond two or three attempts, as this will not fix an underlying hardware fault and can mask important information for your engineer.
- Check for a recent power cut or surge DIY safe
Cast your mind back to whether the home experienced a power outage, flickering lights, or a tripped consumer unit around the time the fault appeared. This information is genuinely useful for a Gas Safe engineer when diagnosing whether the PCB has suffered surge damage versus a mechanical or wiring fault. Note it down before they arrive.
- Have a Gas Safe engineer inspect the HCM and control box connections Gas Safe engineer
A registered engineer will open the boiler casing safely, check that the Heat Control Module is fully and correctly seated in its housing, and inspect all connector plugs and terminals for signs of looseness, corrosion, or damage. This is not a homeowner task — opening the boiler casing yourself is unsafe, may invalidate any remaining warranty, and does not require gas work but does involve live electrical components within a sealed appliance.
- Have the engineer carry out a full PCB and wiring diagnostic Gas Safe engineer
Using specialist diagnostic tools, the engineer will test the PCB for component failures, check wiring looms for shorts or breaks, and look for any evidence of moisture ingress or burn marks. This step determines whether the PCB and HCM can be repaired or whether one or both components need replacing.
- Replace the HCM, PCB, or both if found to be defective Gas Safe engineer
If diagnosis confirms the HCM is faulty, the engineer will source and fit a replacement, ensuring it is correctly matched to the boiler model. If the PCB is the root cause, it will need to be replaced and the boiler re-commissioned and tested. Both jobs require the correct parts, soldering or electronics knowledge, and a full functional test of the appliance before it is returned to service.
- Contact a Gas Safe registered engineer if the fault persists or recurs Gas Safe engineer
If the F0 290 code returns after a single reset, or if the boiler is locking out repeatedly, do not delay booking a qualified engineer. A recurring F0 fault on a Worcester Bosch boiler is rarely self-resolving and will not improve with more resets. Use the Gas Safe Register (gassaferegister.co.uk) to find a registered engineer in your area.
Parts you may need
- Worcester Bosch Heat Control Module (HCM) · from £180
- Worcester Bosch Main PCB · from £220
- Boiler wiring loom / harness · from £55
- Connector plug and terminal repair kit · from £15
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 £200–£450, depending on the underlying cause.
Frequently asked questions
Can I fix the Worcester Bosch F0 290 fault myself?
The only safe DIY steps are attempting one or two resets and making a note of any recent power cuts to share with your engineer. Everything beyond that — opening the casing, inspecting the PCB, checking the HCM connections — must be carried out by a Gas Safe registered engineer. The components involved are live electrical parts inside a sealed boiler, and disturbing them yourself is dangerous and can void your warranty.
How much will it cost to repair an F0 290 fault?
Most people with this fault end up paying somewhere between £200 and £450 all-in, covering the engineer's time and the cost of an HCM or PCB replacement. Labour alone typically runs at £50–£70 per hour depending on where you are in the UK, with London and the South East at the higher end. In rare cases where both the PCB and HCM need replacing together, or where a premium Worcester Bosch model requires specially priced parts, costs can push beyond £500 — but that is not the typical outcome for a straightforward HCM re-seat or single-component swap.
Is it worth repairing my boiler if the PCB has failed?
This depends mainly on the age of your boiler. If it is under eight to ten years old and otherwise in good condition, a PCB or HCM replacement is generally worthwhile. If your boiler is over ten to twelve years old and has had several faults recently, the repair cost may be approaching the point where a new boiler — which will be more efficient and come with a fresh warranty — makes more financial sense. A Gas Safe engineer can give you an honest assessment once they have diagnosed the fault.
Why does the F0 fault code show a three-digit number like 290?
Worcester Bosch uses a two-part coding system. The letters or characters before the number (in this case 'F0') indicate the category of fault — F0 points to an internal control-system error. The three-digit number that follows (290) is the cause code, which tells the engineer precisely which component or subsystem has triggered the fault. In this instance, 290 specifically identifies the control box or Heat Control Module as the source, helping the engineer go straight to the right component rather than having to diagnose from scratch.