Display shows E4 and the refrigerator may not defrost properly, leading to ice buildup on the back wall.

Safety first: Unplug the refrigerator before accessing the freezer evaporator area. Beware of sharp metal fins and residual ice.

E4 typically indicates a problem in the defrost heater circuit on SMEG no-frost refrigerators.

• Step 1 – Confirm symptoms: Check for thick ice on the rear freezer wall and poor cooling in the fridge compartment. This supports a defrost failure.
• Step 2 – Access evaporator: Remove freezer drawers and the rear inner panel. Allow any remaining ice to melt fully.
• Step 3 – Inspect heater and wiring: Locate the defrost heater (often a metal or glass-encased element at the base or woven through the evaporator). Check for burnt spots, broken terminals, or melted connectors.
• Step 4 – Check continuity (advanced DIY): With a multimeter, test the heater for continuity. An open reading indicates a failed heater. Also test any inline thermal fuse or defrost thermostat clipped to the evaporator.
• Step 5 – Replace faulty components: If the heater or thermal fuse is open, replace with the correct SMEG defrost heater assembly or thermostat. Ensure all connections are tight and insulated.
• Step 6 – Reassemble and test: Refit the panel, restore power, and monitor for normal defrost cycles over several days. If E4 returns with a good heater circuit, the main PCB defrost relay or control logic may be faulty and require professional replacement.