BoilerFaultCodesRemeha Er18 Fault Code
Also written as ER18 — same fault.
The Remeha Er18 fault code means: your boiler has detected an unusual temperature reading or a data processing error and has shut down as a safety precaution.. It appears on 1 Remeha model in our database.
Technical description: Technical error data cycle (t1/t2 temperatures) as observed in error memory display
What causes the Remeha Er18 fault?
This fault occurs when the boiler's internal computer detects a conflict between the temperature readings on the flow and return pipes. It is usually caused by a physical failure of the temperature sensors or a communication glitch on the main circuit board that prevents the boiler from safely monitoring heat levels. In some cases, damaged internal wiring can also disrupt these signals, leading the system to shut down for protection.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Remeha models that show the Er18 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha Er18 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