Daewoo Microwave Error Code Er03

Er03 indicates a humidity sensor circuit error that occurs during the auto reheating operation. The control board has detected that the voltage in the sensor circuit is outside the expected range. This fault prevents the auto reheat feature from functioning correctly. The sensor, its connector at CN3, and the associated resistors R6 through R10 are the primary areas to inspect.

When Er03 is active, the auto reheat function is disabled, meaning you should not rely on that feature to properly heat food. Manual cooking modes may still operate, but using the appliance with an unresolved sensor fault is not recommended for extended periods. You should have the sensor circuit inspected before continuing regular use.

Repair costs vary depending on which component has failed. Reseating a connector costs nothing beyond your time. Replacing the humidity sensor typically falls in the range of $20 to $60 for the part alone, plus labor if a technician is used. A control board replacement is the most expensive scenario, generally ranging from $80 to $150 or more for the part. Factor in that a technician diagnostic fee often runs $50 to $100, which may be applied toward the total repair cost.

Some causes of Er03 are accessible to a knowledgeable DIYer. Reseating the CN3 connector and visually inspecting the wiring harness for damage are reasonable first steps that require no special tools. However, testing the specific voltages at points A through D and checking resistor values requires a multimeter and familiarity with circuit boards. If those checks point to a failed sensor or control board, a qualified technician should handle the repair due to the high-voltage components present inside a microwave.

Unplugging the microwave and restoring power may temporarily clear the error display, but Er03 will return as soon as the auto reheat cycle is used again if the underlying fault in the humidity sensor circuit has not been corrected. A reset does not repair a failed sensor, damaged wiring, or defective resistors. Address the root cause to permanently resolve the code.