KitchenAid Microwave Error Code F5

F5 on a KitchenAid microwave means the control board detected that the oven cavity temperature exceeded a safe level. The board monitors this through a cavity temperature sensor. The cause can be either a genuine overheating condition, often from a welded relay keeping heating components on, or a failed sensor sending a false high-temperature reading to the board.

Start by unplugging the microwave and locating the cavity temperature sensor. Check its resistance with a multimeter against the manufacturer's specification and inspect its wiring connector for corrosion or loose pins. If the sensor checks out, the next step is inspecting the control board relays for welded contacts. A welded relay requires control board replacement. If you are not comfortable working inside a microwave, which retains lethal voltage in its capacitor even when unplugged, have a qualified technician perform this diagnosis.

Power cycling may temporarily clear the F5 code, but the code will return if the underlying cause is not repaired. If the fault is a welded relay, the overheating condition will happen again during the next use cycle. Clearing the code without diagnosing and fixing the root cause does not make the unit safe to operate.

No, you should not use the microwave while F5 is active. If the error is caused by a welded relay allowing the magnetron to run uncontrolled, continued use is a fire hazard. Even if the cause turns out to be a faulty sensor giving a false reading, the unit needs to be diagnosed before operating it again to rule out genuine overheating.

If the fix is a faulty cavity temperature sensor, the part typically costs between $20 and $60, and replacing it is a moderate DIY task once the capacitor has been safely discharged. If the cause is a welded relay requiring a new control board, the part alone can run $100 to $250 or more depending on the model, with professional labor adding $100 to $200. On older or lower-end units, total repair cost can approach or exceed replacement cost, so factor in the unit's age before committing to a control board replacement.