Remeha d9 Fault Code

Also written as D9 — same fault.

The Remeha d9 fault code means: your boiler has switched itself off because the water inside is heating up too quickly or too unevenly, which often happens when water cannot circulate through your radiators properly.. It appears on 6 Remeha models in our database.

Technical description: Shut down: maximum temperature rise is exceeded or if the dT between the supply and return temperature ≥ 45°C or a rate of rise in the flow temperature > 1°C/sec.