1( High

Remeha 1( Fault Code

Also written as 1 — same fault.

The Remeha 1( fault code means: your boiler has shut down because the water returning to the unit is too hot, which usually means the water isn't flowing through your radiators properly.. It appears on 14 Remeha models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Return temperature too high

What causes the Remeha 1( fault?

This fault occurs when the water returning from your radiators back to the boiler is at a higher temperature than it should be, causing the system to stop for safety. The most common reason is a restriction in water flow, often caused by a failing pump or debris buildup like iron oxide 'sludge' blocking the internal pipework. It can also be triggered if too many radiator valves are turned off at once, leaving the hot water with nowhere to circulate.

This fault often appears when the heating is first switched on in autumn, as circulation pumps can seize up after being inactive throughout the summer.

Typical repair cost £120-350 (including labour)

DIY fix possible

Check that at least two or three radiator valves (TRVs) are turned to the highest settingEnsure the central heating pump is running and hasn't seizedCheck if any external bypass valves are closed and open them if necessary

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Remeha models that show the 1( fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Remeha 1( 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