Baxi 100he fault Ignition Lockout: hi my baxi boiler has completely stopped working no heating no hot…

Published 12 April 2026 · Generated by BoilerTag's diagnostic AI from an engineer's real-world submission

One of 13 real-world fault checklists on BoilerTag, across 5 boiler makes.

Most likely cause

The Baxi 100HE displaying an 'Ignition Lockout' fault, with no heating or hot water and no noises, indicates the boiler has failed to ignite after several attempts and has entered a safety lockout state. This is a common fault for Baxi 100HE models, particularly after cold weather, and can be caused by various issues including a blocked condensate trap, faulty ignition components, or issues with the gas supply or fan operation.

The engineer's report

A gas engineer submitted this case through BoilerTag's free fault diagnostic tool, working on a Baxi 100he displaying fault code Ignition Lockout. They described the behaviour they were seeing on site as follows:

“hi my baxi boiler has completely stopped working no heating no hot water at all it just has this light on all the time on the display it says ignition lockout but it doesnt make any noises just totally dead. it first did this a couple of weeks ago & now its back again after the cold snap.”

Before requesting the AI diagnostic, the engineer had already worked through the following checks:

“i pressed the reset button a few times but it just stays the same. i checked the pressure gauge & that seems ok and i had a quick look at the white pipe outside that goes into the drain & that looks fine too.”

BoilerTag's diagnostic AI then cross-checked manufacturer documentation and common trade knowledge to produce the prioritised checklist below.

Working on this appliance? Full specs and fault codes for the Baxi Baxi 100 HE → · All Baxi boilers →

Diagnostic checklist

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Commonly failed parts

Condensate trap (if blocked and unable to be cleaned or damaged)
Ignition/detection electrode and lead (Baxi Part No. 173868 or equivalent)
Fan assembly (if faulty)
Gas valve (if faulty)
Printed Circuit Board (PCB) (if other components test as functional and PCB fault is indicated)

More Baxi fault codes

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Sources

The AI cross-checked the following manufacturer and trade sources while producing this checklist.

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This checklist is provided for reference only. Always follow manufacturer documentation and stay within Gas Safe scope. BoilerTag does not replace a qualified engineer's own judgement.

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