BoilerFaultCodesBaxi E118 Fault Code
The Baxi E118 fault code means: your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.. It appears on 7 Baxi models in our database.
Technical description: Primary system water pressure too low (< 0.5 bar).
What causes the Baxi E118 fault?
This fault occurs when the water pressure inside your heating system drops below a safe level, causing the boiler to shut down to prevent internal damage. The most common reasons are a slow leak from a radiator valve or pipework, or air being released from the system through the radiators or an internal auto-air vent.
This issue often appears when you turn your heating back on after summer, as the change in temperature can reveal small leaks or trapped air in the pipes.
DIY fix possible
Locate the filling loop (usually a silver braided hose with two blue-handled valves) underneath the boiler.Slowly open both valves until you hear water entering the system.Watch the pressure gauge and close both valves firmly once the needle reaches between 1.0 and 1.5 bar.
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Baxi models that show the E118 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi E118 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
- Baxi 124 Combi manual (PDF)
- Baxi 600 Combi (range) manual (PDF)
- Baxi EcoBlue Advance Heat manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026