Refrigerator shows E4 and there is heavy frost or ice buildup on the freezer back wall

Safety first: Unplug the refrigerator. The defrost circuit operates at mains voltage and can be hazardous.

Step 1 – Manually defrost:

• Open the freezer door and remove all food.
• Leave the door open and allow ice to melt naturally, or place bowls of hot water inside to speed up the process.
• Do not chip ice with sharp tools to avoid puncturing the evaporator.

Step 2 – Access the defrost components:

• Remove the inner rear freezer panel to expose the evaporator coil.
• Locate the defrost heater (usually a metal or glass tube at the bottom or woven through the coil) and the defrost thermostat clipped to the coil.

Step 3 – Test the defrost heater:

• Disconnect the heater leads.
• Measure resistance with a multimeter; typical values are between 20–200 Ω depending on design.
• An open circuit indicates a failed heater that must be replaced.

Step 4 – Test the defrost thermostat:

• While the thermostat is cold (below freezing), check continuity across its terminals.
• No continuity when cold indicates a faulty thermostat.

Step 5 – Replace faulty parts:

• Order the correct defrost heater and/or thermostat for your Brandt model.
• Install the new components in the same positions and reconnect wiring securely.
• If both test good, the main control board’s defrost relay or logic may be defective and the board may need replacement.

Step 6 – Reassemble and monitor:

• Reinstall the rear panel and shelves.
• Restore power and monitor for several days to ensure frost does not re‑accumulate and that E4 does not return.