**Given the repeated flame failure and your check at the pressure test point, leave the boiler off and arrange a Gas Safe registered engineer.** If you loosened or opened that test point, tell the engineer so they can check that it is sealed and gas-tight before use.

The useful diagnostic detail is **whether the flame goes out while you’re holding the pilot button down, or only after you release it**:

- **Only after releasing it:** the thermocouple may have had insufficient time to heat, the pilot flame may be too weak to heat it properly, or the thermocouple or valve’s safety magnet may be faulty.
- **While still holding it down:** the engineer should investigate pilot gas flow, including a restricted pilot jet or tubing, and the valve’s operation.

The Honeywell V4600 family uses a thermocouple heated by the pilot to hold the safety valve open. Its handbook describes holding the button down for 20 seconds after ignition and waiting at least three minutes after a failed attempt. Your boiler’s own lighting instructions take precedence. These symptoms alone cannot establish which component has failed. [Honeywell handbook, pp. 19–21](https://honeyvell.ru/files/documents/Honeywell%20V46xx,%20V86xx%20handbook%20(eng).pdf)

The working gas fire confirms gas reaches that appliance. Gas at the boiler inlet does **not** establish adequate operating pressure or gas flow through the pilot circuit.

For now, find the boiler’s make, model and lighting instructions, and check any available service records. Leave pilot cleaning, pressure adjustments and thermocouple work to the engineer; never bypass the flame safety device. Given its unknown history, ask for a service and flue safety check as well. [HSE guidance](https://www.hse.gov.uk/gas/domestic/faqs.htm)

**If you smell gas or suspect a leak**, stop lighting attempts, avoid electrical switches and flames, open doors and windows, turn off gas at the meter if safe, and call **0800 111 999 in Great Britain** or **0800 002 001 in Northern Ireland**. [Gas Safe emergency guidance](https://www.gassaferegister.co.uk/media/3570/32492_gsr_lit_guidetosafety_a5_aw1_l6p12-21v1-2.pdf)