Boiler displays E08, no heating or hot water, pump may run briefly then stop.

Safety: Turn off power and allow the boiler to cool. Close isolation valves before opening any wet components.

• Check for air: Bleed air from the boiler via the automatic air vent on top of the Defro heat exchanger (loosen cap slightly) and from radiators. Ensure system pressure is correct.
• Free the pump: Locate the Defro circulation pump. Many pumps have a central screw cap. With power off and a cloth ready for small leaks, remove the cap and insert a screwdriver into the rotor slot. Gently turn to free a stuck rotor, then refit the cap.
• Clean system filter: If a Defro return filter is fitted, isolate, open, and clean out sludge and debris. Reopen valves and repressurize the system.
• Test operation: Restore power and call for heat. If the pump still does not run or E08 returns, the pump motor or control board output may be defective and should be tested by a technician.