BoilerFaultCodesRemeha 18-19 Fault Code
Also written as 1819 — same fault.
The Remeha 18-19 fault code means: your boiler has lost water pressure or cannot detect enough water to operate safely, causing it to shut down to prevent damage.. It appears on 3 Remeha models in our database.
Technical description: Water level control
What causes the Remeha 18-19 fault?
This fault occurs when the system's internal sensors detect that the water pressure has dropped too low for the boiler to operate safely. The most common reasons are a leak somewhere in the pipework or radiators, or an expansion vessel that has lost its air charge and can no longer stabilize the pressure. In some cases, the water pressure sensor itself may have failed or become blocked with system debris.
This issue is more frequent in autumn when the heating is turned back on after a long break, as underlying leaks or pressure drops often become apparent during the first full cycle.
DIY fix possible
Check the pressure gauge on the boiler or pipeworkUse the external filling loop to top up the system pressure to 1.5 barEnsure all radiator valves and system isolation valves are fully openRestart the boiler once the correct pressure is reached
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Gas Safe Register →Remeha models that show the 18-19 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha 18-19 fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026