Samsung Microwave Error Code E-21

E-21 on a Samsung microwave is a temperature sensor open error, meaning the control board cannot detect a signal from the temperature sensor. The fault indicates an open circuit in the sensor or its wiring. The microwave will not function normally until the sensor circuit is repaired or the failed component is replaced.

It is not recommended to operate the microwave while E-21 is active. The temperature sensor provides the control board with thermal data used to manage cooking and prevent overheating. Running the unit without a functioning sensor could result in uncontrolled temperature conditions or additional component damage.

Repair costs depend on the root cause. A replacement temperature sensor part typically ranges from roughly $15 to $50 depending on the model. If professional labor is involved, total repair costs including diagnosis and parts can range from $80 to $200 or more. If the main PCB is the failed component, parts and labor costs will be toward the higher end of that range.

Some causes of E-21 are accessible to a knowledgeable DIYer, such as reseating a loose connector between the sensor and the PCB. However, replacing the temperature sensor or diagnosing wiring damage requires comfort working around microwave components. Note that microwaves contain a high-voltage capacitor that can retain a dangerous charge even when unplugged, so discharge the capacitor before touching any internal parts.

A reset, such as unplugging the unit for a few minutes and powering it back on, may temporarily clear the code from the display. However, if the underlying cause is a failed sensor or broken wiring, the E-21 error will return once the microwave attempts to read the sensor again. A reset alone does not repair the fault.