BoilerFaultCodesYour boiler is currently stuck in a diagnostic test mode that overrides its normal settings, which usually happens during a service or repair.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Set diverter valve position
What causes this fault?
This code appears because the boiler has been manually instructed to hold its internal diverter valve in a specific position for testing purposes. This usually happens during a professional service when a technician needs to isolate the heating or hot water circuits to check for leaks or performance issues. If the code remains on the screen, the boiler has simply not been exited out of this specific diagnostic menu.
DIY fix possible
Locate the display panel on the front of the boilerPress the 'Reset' button (marked with a flame or cross symbol) for one secondWait for the boiler to restart and check if the 'D.70' code has disappeared
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