Boiler stops heating and displays E02; unit may attempt to start and then shut down quickly

Safety first: Turn off power at the boiler switch and the main breaker. Allow the boiler to cool completely (at least 30–60 minutes) before touching internal components.

Steps to check:

• Confirm system pressure and circulation: Ensure the system pressure is within the recommended range and that all radiator valves and isolation valves are open to allow flow.
• Reset the overheat thermostat: Remove the front panel. Locate the manual reset safety thermostat (usually mounted on or near the heat exchanger on Kospel electric boilers). Press the reset button firmly until you feel a click.
• Check the circulation pump: With power off, inspect the circulation pump for signs of blockage or seizure. Gently turn the pump shaft (if accessible) with a screwdriver to ensure it moves freely.
• Inspect filters and strainers: Clean any system strainers or Y-filters on the return line to the boiler that may be restricting flow.
• Restart and monitor: Restore power and call for heat. Monitor the temperature rise. If E02 reappears quickly, there may be a serious circulation or scaling issue.

When to call a technician: Persistent E02 after reset, or evidence of severe limescale in the heat exchanger, requires professional descaling or component replacement.