Boiler displays E10; the pressure gauge may be low or flashing, and the boiler will not run.

Safety first: Allow the system to cool before topping up pressure to avoid scalding.

Step-by-step user fix:

• Check the pressure gauge on the boiler. If below 1.0 bar (cold), you need to re-pressurise.
• Locate the filling loop (usually a silver braided hose with two valves). Open both valves slowly until the gauge reaches 1.2–1.5 bar, then close both valves firmly.
• Reset the boiler and check its operation.
• Walk around the property and inspect visible pipework, radiators, and valves for signs of leaks (stains, drips, green/white crust).

If pressure keeps dropping:

• Do not keep topping up daily; this can damage the boiler.
• A heating engineer should check for hidden leaks, test the expansion vessel, and verify the pressure sensor.