E18
Bosch Defrost Timer or Control Fault

Ice buildup in freezer, poor cooling, E18 error

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Defective defrost control logic on main board, Stuck defrost relay, Incorrect defrost interval programming, Wiring fault to defrost components

How to Fix / Troubleshooting

Safety first: Unplug the refrigerator before accessing control boards or evaporator area.

Immediate relief:

  • Manual defrost: Remove food, unplug the unit, and allow all ice to melt (12–24 hours). This will temporarily restore airflow and cooling.

Further steps:

  • Verify defrost components: Before blaming the control, test the defrost heater, sensor, and thermal fuse for continuity and proper resistance. Replace any failed parts.
  • Inspect control board: Access the main control (usually at the rear or top). Look for burnt components or corrosion.
  • Reset: Some Bosch models allow a forced defrost or control reset via button combinations (see service manual). Attempt a reset after manual defrost.

Note: If all defrost hardware is good and E18 recurs, the main control board likely needs replacement by a professional.

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Repair Difficulty

Hard 4/5

Required Part

Main Control Board
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