Error F0 290

{ "ai_overview": "F0 290 on a Worcester Bosch GB162 is a fault indicating a problem with the burner control electronics (often called the KIM or burner control unit) or a related analogue/digital (A/D) converter reference error. In practice this means the boiler’s control board is detecting an internal electronic fault or incorrect/damaged control module that prevents safe ignition and normal burner operation. The fault can arise from a failed control board, a bad A/D converter on the board, a loose or incorrectly fitted heat control module (HCM / code plug), water ingress into the burner control box, or occasionally a software/firmware issue or incorrect replacement part after servicing.\n\nSeverity is moderate-to-high because it affects burner control and ignition safety: the boiler will typically lock out and stop providing heating/hot water until the fault is resolved. This is primarily an electrical/electronic safety and control issue rather than a simple mechanical fault, so it is not a routine DIY repair. Homeowners can perform a few basic, non-intrusive checks (reset, power checks, visual inspection for obvious damage or water) but any internal inspection, component replacement, or work involving gas/electrical connections should be carried out by a qualified Gas Safe registered engineer.", "troubleshooting": "Safety precautions:\n- Do not attempt to work on gas pipes, gas valves, ignition parts, or internal electrical components unless you are a Gas Safe qualified engineer. Incorrect work can cause gas leaks, fire or carbon monoxide risk.\n- Before touching the boiler, isolate the electrical supply at the external switch or consumer unit. If you are unsure where this is or how to isolate safely, do not proceed.\n- Keep the area ventilated and do not run the boiler if you suspect a gas smell; if you smell gas, turn off the gas supply at the meter (if safe to do), leave the building and call the gas emergency number immediately.\n\nInitial homeowner checks (safe, non-intrusive):\n1. Note the displayed code and any flashing symbols. Some boilers also show a cause code in the info menu (press the spanner/return button) — write this down for the engineer.\n2. Try a simple reset: press and hold the boiler reset button (or follow the model-specific reset procedure) for 3 seconds. Wait and see if the boiler attempts to restart. Do not attempt repeated resets more than a couple of times; continuous resets can hide the root cause and stress components.\n3. Check that the boiler has power: check the external isolation switch and household fuses. Ensure any room thermostat or timer calling for heat is set correctly.\n4. Check visible external connections and condition: look for obvious water leaks, corrosion, soot, or signs of recent condensate overflow. If you see water in or around the burner control box or extensive corrosion, power down and inform the engineer — water damage commonly causes control faults.\n5. If the boiler was recently serviced or a part was recently replaced (HCM / coding card / control module), make note of that — incorrect or incompatible parts are a known cause of this code.\n\nHomeowner-level diagnostic steps you can do only if competent and comfortable, and after isolating mains power:\n- With mains power isolated, you may check that connectors and code plug on the HCM appear fully seated and that wiring looms are not visibly loose or damaged. Do not remove or probe internal components unless you are confident and understand isolation procedures. If any connectors are loose, leave the boiler powered off and call a Gas Safe engineer to re-seat and test properly.\n- Do not open gas-valve, burner or ignition assemblies. Do not attempt PCB repairs or component replacements.\n\nWhen to call a professional (required in most cases for F0 290):\n- If reset does not clear the fault, or if the fault returns, contact a Gas Safe registered Worcester Bosch engineer. This code usually requires professional diagnosis and replacement of the burner control unit/KIM, replacement of the HCM/code plug if incorrect, or replacement/repair of the main PCB or its A/D converter components.\n\nWhat a Gas Safe engineer will typically do (diagnostic and repair steps they perform):\n1. Run the boiler’s service diagnostic menu to read fault and cause codes and detailed status messages.\n2. Check for recent software updates or known firmware issues and re-flash/update software where applicable.\n3. Inspect the burner control box (KIM), main PCB and HCM/code plug for water ingress, burnt components, loose connectors or damaged traces.\n4. Measure voltages and analogue/digital signals around the A/D converter and associated resistors; replace the PCB or KIM if A/D circuitry has failed.\n5. Verify the correct HCM/coding card is fitted for the specific GB162 variant and replace with the correct module if wrong or defective.\n6. Replace the burner control unit / KIM or main control PCB if diagnostics show component failure, then run ignition and safety checks, test combustion, and verify all sensor inputs and safety interlocks operate correctly.\n7. Record the fault, fix and any parts replaced on the service report, and advise on prevention (e.g. ensuring condensate/water does not enter the burner control box, correct part fitment at service).\n\nFinal notes:\n- Do not continue to reset the boiler repeatedly to force operation — this can mask faults and increase risk. If the fault persists after basic checks, arrange an emergency or non-emergency visit from a Gas Safe registered Worcester Bosch-trained engineer.\n- Provide the engineer with the exact fault and cause codes, and tell them about any recent servicing, part changes, or evidence of water ingress — this will speed up diagnosis.\n- If you need help locating a Gas Safe engineer, contact Worcester Bosch support or use local Gas Safe registration services.