BoilerFaultCodesWhat the manual says
Manufacturer manualTemperature difference between supply and return exceeding limit
From this model's manual
Verified against the Worcester Bosch/Worcester Bosch Greenstar 12i System installation & service manual.
DIY fix possible
Check that your radiators are getting warm and bleed any that have trapped air inside them.Verify that all radiator valves (both manual and thermostatic) are fully open to allow good water flow.Check that your system pressure is correct, typically between 1.0 and 1.5 bar when the boiler is cold.
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