BoilerFaultCodesRemeha E11 Fault Code
The Remeha E11 fault code means: your boiler has detected that water is returning much colder than it left, usually because it isn't moving through your radiators properly.. It appears on 8 Remeha models in our database.
Technical description: Delta T (Return - Flow) too large
What causes the Remeha E11 fault?
This fault occurs when the water isn't flowing through your heating system fast enough, causing a large temperature gap between the outgoing and incoming pipes. The most common reasons are a failing internal pump that can't push the water around or a blockage in the system, such as a build-up of sludge or a closed valve. When the boiler detects this imbalance, it shuts down to prevent the heat exchanger from overheating.
This issue often comes to light during the first cold spell of autumn when the heating is turned on after being dormant all summer, as pumps are prone to seizing during long periods of inactivity.
DIY fix possible
Check that all radiator valves (TRVs) are fully openEnsure your central heating pump is running and hasn't seizedBleed all radiators to remove trapped air that might be blocking water flow
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Gas Safe Register →Remeha models that show the E11 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha E11 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