Symptoms
• Refrigerator and freezer compartments not cooling to the set temperature
• Error code E21 displayed on the digital control panel
• Compressor running continuously without proper temperature regulation
• Food items not staying cold or beginning to spoil
• Freezer compartment not reaching 0°F as expected
• Unusual beeping or alarm sounds from the refrigerator
• Interior light functioning normally but cooling system not working
Possible Causes
• Faulty evaporator temperature sensor (most common cause on USA Bosch models)
• Damaged or loose wiring harness connecting the sensor to the main control board
• Evaporator fan motor failure or improper operation
• Control board malfunction affecting sensor signal processing
• Ice buildup on the evaporator coils blocking proper air circulation
• Defective thermistor in the temperature sensing circuit
• Poor electrical connection at the 120V outlet due to loose plug or tripped breaker
• Control module experiencing a communication error with the refrigeration system
Safety Checks You Can Do
• Verify the refrigerator is plugged into a dedicated 120V outlet and check that the outlet has power by testing another appliance
• Check your home's electrical circuit breaker panel to ensure the breaker for the refrigerator circuit has not tripped; reset if necessary
• Perform a hard reset by unplugging the refrigerator from the wall outlet for 60 seconds, then plug it back in to clear any temporary errors
• Verify the refrigerator is level on the floor using a spirit level; adjust the front leveling feet if needed to ensure proper drainage and cooling function
• Inspect the door seals and gaskets on both the refrigerator and freezer compartments to ensure they are clean, flexible, and creating an airtight seal when closed
• Check the temperature setting on the digital control panel and confirm it is set within the recommended USA range of 35-38°F for the refrigerator compartment and 0°F for the freezer
• Unplug the unit and inspect the condenser coils at the back or bottom of the refrigerator for dust and debris buildup; gently vacuum if excessive dust is present
• Ensure the refrigerator has at least 2 inches of clearance on all sides and adequate ventilation space, particularly at the back and bottom where air circulation is critical
• Verify the ice maker and water line connections are functioning properly and not causing frost accumulation in the freezer section
• Monitor the refrigerator for 30 minutes after the reset to see if the error code reappears or if normal cooling function resumes
Safety First
Always disconnect the appliance from power before performing any checks. If you are unsure about any step, please contact a qualified technician.