Frigidaire Microwave Error Code F91

F91 indicates a door motor mechanism failure on a Frigidaire microwave. It falls within the F90 to F94 fault range, all of which relate to the motorized door latch system. The control board detected that the lock motor, lock switch, or door switch did not respond as expected during a door locking sequence. The microwave will not operate until the fault is resolved.

No, you should not attempt to operate the microwave while the F91 fault is active. The door motor mechanism is part of the safety interlock system that ensures the door is properly latched before microwave energy is generated. A failure in this system means the microwave may not be safely secured, and operating it in this condition is a safety risk.

Repair costs vary depending on which component has failed. Replacing a lock switch or door switch is generally the least expensive fix, typically ranging from around $50 to $150 including parts and labor. A lock motor replacement may cost somewhat more, in the range of $80 to $200. If the control board is at fault, replacement costs can range from $150 to $350 or higher depending on the model and service rates in your area.

A power reset is the recommended first step and can clear the F91 code if the fault was caused by a temporary control board glitch. Turn off power to the microwave for at least 10 seconds, restore power, and then try starting a Clean cycle to test the door latch. If the error returns after the reset, there is a genuine hardware failure in the lock motor, lock switch, door switch, or associated wiring that requires further diagnosis.

Start by turning off power for 10 seconds and then restoring it, then attempt to start a Clean cycle to see if the door latch responds. If the fault returns, inspect the wiring and connectors on the lock motor, lock switch, and door switch circuits for damage or loose connections. If wiring appears intact, each component should be tested individually to identify which one has failed and needs replacement. Because this repair involves working near high-voltage components inside a microwave, many technicians recommend having a qualified repair professional perform the inspection.