Your boiler has stopped because it could not light its burner safely, so it has shut itself down to protect your home and it will not heat your water or radiators until a qualified engineer checks it.

Fault EE (shown when ignition, gas train opening or ionisation current build-up fails). Ignition: Check ignition module (control voltage 230 V across plugs "X2.1" and "X2.2"). Check the gas supply. Gas train opens: Check the gas train (control voltage 230 V~); check the gas supply pressure. Ionisation current builds: Check setting of ionisation electrode. Purge the gas line.