Boiler shows code 4, burner off, pump may run briefly, no heating or hot water

Information: Code 4 on many Intergas models indicates no current demand rather than a fault. If you expect heat or hot water and see code 4, the issue is likely with external controls.

• Check programmer: Confirm the heating and hot water programs are set correctly and currently in an 'ON' period.
• Check room thermostat: Turn the thermostat up to maximum. If the boiler does not leave code 4, the thermostat or its wiring may be faulty.
• Check hot water: Open a hot water tap fully. On combi models, the boiler should detect flow and change state. If it remains on 4, the flow sensor or PCB input may be faulty.
• Inspect wiring centre: With power isolated, visually check for loose or disconnected thermostat/programmer wires in the wiring centre (if accessible). Do not touch live wiring.
• Engineer involvement: If controls are confirmed working but the boiler stays on 4, a technician should test the low-voltage demand circuits and PCB.