Geo Gas Services London Ltd provides reliable gas, boiler, plumbing, drainage, building works and carpentry support across London and surrounding areas.

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Geo Gas Services London Ltd delivers gas, boiler, plumbing, drainage, building works and carpentry support with rapid emergency response.

Boiler fault guide

Why Is My Boiler Not Igniting?

If your boiler is not igniting, the appliance is failing to light and start the heating cycle properly. The cause may be simple, but repeated failure to ignite needs proper diagnosis.

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What ignition failure means

Ignition failure means the boiler is not completing the normal firing sequence. That can be caused by pressure issues, electrical faults, failed components or brand-specific lockout behaviour.

Why the boiler may stop firing

Low system pressure, faulty ignition parts, sensor issues and controls faults are all common reasons a boiler will not light when called for heat.

When this becomes urgent

If you have no heating or hot water and the boiler repeatedly locks out, book a repair visit rather than continuing to reset it and hope it recovers.

Do not DIY these repairs

  • Do not interfere with ignition parts or gas components
  • Do not dismantle the boiler casing
  • Do not keep resetting the boiler over and over

What usually fixes it

  • Repairing ignition or detection faults
  • Restoring correct pressure and controls operation
  • Resolving component or electrical issues affecting start-up

Frequently asked questions

Is this something I should ignore for now?

No. Boiler and heating faults usually get worse if the underlying cause is left unresolved, especially if the boiler is shutting down or leaking.

Can I safely diagnose the internal fault myself?

No. You can carry out basic visual checks, but internal boiler parts and gas-related work should be left to a qualified engineer.

Will this automatically mean I need a new boiler?

Not always. Many common faults can be repaired once the real cause has been identified.

Related pages

Need the fault diagnosed?

Book a boiler repair visit

If the problem keeps returning or your heating has stopped, book a proper diagnosis from a Gas Safe engineer.

Common symptoms

  • Boiler tries to start but does not fire
  • Repeated lockouts or fault codes
  • No heating and no hot water

Safe checks

  • Check whether there is power to the boiler and controls
  • Check the room thermostat or programmer settings
  • Look for obvious low-pressure warnings on the display