Error F0 290

Safety precautions:

1. If you smell gas, turn off gas supply at the meter, do not operate electrical switches, open windows, leave the property and call the gas emergency line immediately. Do not attempt internal checks.

2. If you are not competent with electrical or gas appliances, do not open the boiler. Only perform visual, non-invasive checks. Any work on the boiler internals must be carried out by a Gas Safe registered engineer.

3. Before any simple checks that involve touching external controls, switch the boiler off at the mains and allow a short time to cool if it has been running.

Initial homeowner checks you can safely do:

1. Note the exact error code and any cause code or additional messages shown on the display. Take a photo of the display and write down any other symptoms (no heating, no hot water, any unusual noises).

2. Check mains power: ensure the boiler has power (front display lights). Check the house fuse and any fused spur supplying the boiler.

3. Try a basic reset: follow the Greenstar reset method for your model — usually press and hold the reset button for about 3 seconds, or use the quick-reset position on the temperature dial as per your manual. Wait for the boiler to attempt to restart and observe whether the same F0 290 returns.

4. Use the quick info/spanner button on the boiler to view the cause code/history if available. Record any cause code shown.

5. Check external controls: make sure the thermostat or programmer is calling for heat/hot water as expected. Turn room thermostat up and see if the boiler responds (but do not attempt more than simple on/off commands).

Specific diagnostic steps and non-invasive checks (only if comfortable and the boiler is isolated from mains):

1. Visual inspection of the case and connections: with the boiler powered off at the mains, open the outer casing only if you are competent to do so and it is safe to access. Look for obvious signs of damage, burn marks, loose connectors or a detached coding card/HCM plug. Do NOT probe or touch live components.

2. Check the Heat Control Module (HCM) / code plug seating: many Greenstar models use a small module or card plugged into the control box. Sometimes vibration or movement can cause poor contact. If you are experienced and the mains is isolated, gently reseat the HCM/code plug (remove and refit) ensuring connectors are aligned. If you are not sure, stop and call an engineer.

3. Inspect wiring to the control box for any loose plugs or disconnected leads. Re-seat any obviously loose connectors (only when power is removed). Document which connectors you touch and how they were connected.

4. After re-seating and reassembly, restore power and try a reset again. If the error clears and the boiler runs normally for a period, continue to monitor. If the fault returns, power down and call a Gas Safe engineer.

5. If the display reports related codes (9U, C4, A8 etc.) these also indicate control box/HCM or coding card issues and strengthen the need for component replacement.

When to call a professional and what to tell them:

1. Call a Gas Safe engineer if the F0 290 persists after a single safe reset, if you found loose or damaged components, or if you are not confident to carry out the brief checks above.

2. When you call, provide: boiler model and serial number, the exact fault code (F0 290), any cause codes from the info menu, a description of steps you have already taken (reset, reseated HCM, photos), and any other symptoms.

3. Repairs likely required by an engineer: full diagnostic with meter and service tools, testing and possibly replacement of the control box/PCB, HCM/code plug, or rectifying wiring/connector faults. The engineer will also carry out safety and combustion checks after repair.

Important notes:

1. Do not attempt to modify or bypass safety devices, and do not replace the gas control or PCB yourself — these are gas-bearing and electrically live parts requiring a Gas Safe professional.

2. A transient electronic fault can sometimes be cleared by a reset, but repeated occurrences indicate a failing control component or intermittent electrical connection and need professional attention.

3. Keep evidence (photos, notes) of the fault and any checks you made — this helps the engineer diagnose faster on arrival.