Main Heating · Eco Compact Combi 25–30
118 boiler fault code
Main Eco Compact Combi models 25–30
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What 118 means
Primary system water pressure too low.
Safe check
Read and note code 118 or E118 and the visible pressure reading. If it is below 1.0 bar, follow only the Main Eco Compact Combi 25–30 user guide pressure instructions on printed page 14; stop if unsure.
When to contact an engineer
Arrange a Gas Safe registered engineer if the pressure will not hold, falls again, or the guide procedure is unclear.
Safety notice
A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, anyone feels unwell, or there is an unsafe flame, leave and call 0800 111 999 from outside.
Source and provenance
- Main Eco Compact Combi User Guide · models 25–30 · pressure instructions p. 14; §7.1, printed p. 21
user guide
Model 25–30; document copy publishes no revision
- Baxi Professional error-code table · legacy Baxi 600 Combi & System group
professional error-code table
Checked 29/09/2026; the online table publishes no revision
Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.
Did this fix it?
After: Repressurise the boiler