DIAGNOSIS The most common cause is cold internal components. The brew group and cups must be preheated. A secondary cause is a scaled heat exchanger.
FIX Execute a proper warm-up cycle. Turn the machine on from a cold start. Do not immediately brew. Allow it to complete its automatic rinse. Then, run two cycles of hot water only from the spout into an empty cup. This heats the internal circuit. Now brew your coffee.
IF THAT DIDN'T WORK Perform a descaling procedure. Limescale buildup on the thermoblock significantly reduces heating efficiency. Use only De'Longhi EcoDecalk or a certified descaling solution for this model.
HEADS UP The 'High' temperature setting applies only after the machine is at operating temperature. It does not accelerate the initial warm-up.