BoilerFaultCodesBaxi 118 Fault Code
The Baxi 118 fault code means: your boiler has detected that there is not enough water in the system to operate safely, causing it to shut down temporarily.. It appears on 24 Baxi models in our database.
Technical description: Water pressure too low
What causes the Baxi 118 fault?
This fault occurs when the internal sensors detect that the water pressure has dropped below the minimum level required to circulate heat safely. The most common reason is a small leak somewhere in the central heating pipework or radiators, though it can also happen if you have recently bled your radiators without topping the system back up.
This fault is frequently seen in autumn when homeowners turn their heating back on for the first time, as the system struggles to reach pressure after a long period of inactivity.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the one or two taps/valves on the filling loop until you hear water entering the system.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps fully.
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Baxi models that show the 118 fault code
Click a model for the full fault code list and model-specific repair notes.
- 124 Combi Repair: £0-160
- 128 Combi Repair: £0-160
- 615 System 15
- 618 SYSTEM
- 624 System 24
- 818 System
- 824 SYSTEM
- Assure Repair: £0-£120
- Duo-tec 2 Combi 28 Compact
- Duo-tec Combi GA Repair: £0-160
- EcoBlue Repair: £0-120
- Ecoblue 12 System ErP
- Ecoblue 15 System ErP
- Ecoblue 24 System ErP
- Ecoblue 28 System ErP
- Ecoblue Advance Combi Repair: £80-150
- EcoBlue System Repair: £80-150
- Ecoblue18 System ErP
- Neta-tec Combi 24 GA
- Neta-tec Combi 28 GA
- Neta-tec Combi 33 GA
- PLATINUM COMPACT 25 COMBI
- PLATINUM COMPACT 30 COMBI
- PLATINUM COMPACT 36 COMBI
Source
Baxi 118 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026