Boiler displays D5, often related to diverter valve or motorised valve issues.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Stuck diverter valve, Failed diverter motor, Scale or debris in valve body, Faulty position feedback switch

Safety first: Turn off power and isolate water supplies before working on valves.

Symptom check: You may notice heating but no hot water, or vice versa, when D5 appears.
Exercise the valve: Run hot water and then heating to encourage the diverter valve to move. Sometimes light tapping on the valve body can temporarily free a sticking valve (do not hit hard).
Engineer repair: A technician should remove and inspect the diverter valve, clean or replace the cartridge, test the motor and microswitches, and flush debris from the system.

Hard 4/5

Diverter Valve Assembly

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