How to Fix a Boiler Not Igniting
Last updated: 30 September 2026
Check the gas supply, check the condensate pipe, check the pressure, then reset the boiler once.
Overview
A boiler that will not ignite leaves you without heating or hot water. This guide covers common causes and safe checks before calling an engineer.
Step-by-Step Fix
Before beginning any repair, ensure you have isolated power or water supplies. Clear your workspace, gather standard hand tools, and wear appropriate personal protective equipment (PPE).
- First check whether your other gas appliances are working. Turn on a gas hob or gas fire. If they work normally the gas supply to your property is fine. If they do not work there may be a gas supply issue that requires contacting your supplier.
- Check the boiler pressure gauge. The pressure should read between one and one point five bar when the system is cold. If it is below one bar repressurise the system using the filling loop. Low pressure can prevent the boiler from firing.
- Check the condensate pipe for ice or blockages. The condensate pipe is the white or grey plastic pipe running from the boiler to an outside drain. In winter this pipe can freeze causing the boiler to lock out. If the pipe is frozen thaw it by pouring warm water over the pipe.
- Check the boiler display for error codes. Common codes include EA which indicates ignition failure and E119 which indicates low pressure. Note the code and consult your boiler manual. Some codes indicate issues you can resolve yourself while others require a Gas Safe engineer.
- Press the reset button on the boiler once. The reset button is usually marked with a circular arrow. Hold it for three seconds. If the boiler fires and runs normally the issue is resolved. If the boiler does not fire or the error code returns do not keep pressing reset.
- Check that the thermostat is calling for heat. The thermostat should be set higher than the current room temperature. If the thermostat is set too low the boiler will not fire. Check that the timer is set correctly.
- If you have a combi boiler check that the hot water tap is calling for hot water. Combi boilers fire on demand for hot water. If the boiler is not firing when the hot tap is turned on there may be a fault with the diverter valve or flow sensor.
- If the boiler still does not ignite after these checks there is likely an internal fault. Common causes include a faulty gas valve, a faulty ignition electrode, a faulty fan, or a faulty PCB. These are all internal components that must only be worked on by a Gas Safe registered engineer.
- Turn off the boiler and call a Gas Safe registered engineer. Explain the error code and any symptoms you have observed. Do not attempt to open the boiler casing or work on any gas components. This is dangerous and illegal unless you are registered.
- To prevent future ignition problems have your boiler serviced annually by a Gas Safe registered engineer. Regular servicing keeps the boiler running efficiently and identifies potential issues before they become serious faults.
Common Error Codes
Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.
| Symptom / Code | Likely Root Cause | Recommended Resolution |
|---|---|---|
| EA | Ignition failure, boiler tried to light but no flame detected | Check the gas supply and condensate pipe. Reset the boiler once. If the code returns call a Gas Safe engineer. |
| E119 | Low system pressure preventing ignition | Repressurise the boiler using the filling loop to between one and one point five bar. |
| F28 | Ignition fault on Vaillant boilers | Check the gas supply. If gas is present and the code persists call a Gas Safe engineer. |
| E133 | Ignition fault on Baxi boilers | Check the gas supply and condensate pipe. Reset the boiler. If the code returns call a Gas Safe engineer. |
Frequently Asked Questions
Why is my boiler not igniting?
Common causes include a lack of gas supply a frozen condensate pipe low boiler pressure a faulty ignition electrode or a faulty gas valve. Some causes can be checked safely yourself while others require a Gas Safe engineer.
Can I fix a boiler that will not ignite myself?
You can check the gas supply to other appliances check the pressure repressurise if needed check the condensate pipe and press reset once. Any work inside the boiler must be done by a Gas Safe registered engineer.
Why does my boiler not ignite in winter?
The most common cause in winter is a frozen condensate pipe. The condensate pipe carries water away from the boiler and can freeze in cold weather causing the boiler to lock out. Thaw the pipe with warm water to resolve the issue.
What does EA error mean on a boiler?
EA indicates ignition failure. The boiler has tried to light but has not detected a flame. Common causes include a lack of gas a blocked condensate pipe or a faulty ignition component. Reset once and call an engineer if the code returns.