Microwave
error codes,
read properly.

The control cannot agree with itself about whether the door is shut. A microwave checks its door with several interlock switches behind the latch, and it refuses to heat unless every one reports the same thing; a hook that has worn, a switch that sticks or a door knocked out of line leaves them disagreeing. Sometimes a firm close clears it, but a code that keeps returning, or a microwave that hums with the door open, is taken out of use until the switches are tested.

Usually leads to

Microwave door switch and latch repair

Shows up as

Microwave Won't Turn On at AllMicrowave Door Won't Latch ShutMicrowave Runs With the Door OpenWhat a Microwave Error Code Is Telling You

The microwave ran a cycle and the control saw no heat come of it, or saw the power section behave strangely. The cause sits somewhere in the chain that makes the energy: the magnetron, the high-voltage diode and capacitor, the transformer that feeds them. All of it lives behind the outer cabinet, where a capacitor keeps a dangerous charge even unplugged, so after a restart the owner's part ends at booking the visit.

Usually leads to

Microwave magnetron repair

Shows up as

Microwave Runs but Food Stays ColdLoud Hum, Buzz or Grinding From a MicrowaveSparks Flashing Inside a MicrowaveWhat a Microwave Error Code Is Telling You

The control has stopped trusting what one of its sensors reports: the cook or humidity sensor that ends a sensor reheat when steam rises, or a thermal cutout that trips when the cavity or the magnetron runs too hot. A cutout that opens stops the microwave mid-cycle and often recovers once it cools; one that keeps tripping, or a sensor program that shuts off at once every time, needs the sensor, its wiring or the airflow behind it checked.

Usually leads to

Microwave control board and touchpad repair

Shows up as

Microwave Shuts Off Before the Timer EndsMicrowave Runs but Food Stays ColdMicrowave Won't Turn On at AllWhat a Microwave Error Code Is Telling You

A fan the microwave depends on has slowed or stopped: the cooling fan that keeps the magnetron and the board from overheating, or on a hood combination the exhaust fan that draws steam up through the grease filters. A filter packed with grease or a damper stuck shut can bring on the same warning, so a clean filter comes first; a motor that hums without turning, or a warning that returns with clean filters, is a repair.

Usually leads to

Microwave vent fan and filter repair

Shows up as

Microwave Vent Fan Not Pulling SteamLoud Hum, Buzz or Grinding From a MicrowaveMicrowave Shuts Off Before the Timer EndsWhat a Microwave Error Code Is Telling You

The electronics that read the keys and run the cycle have flagged a problem with themselves: a key that the control sees as held down for too long, a membrane keypad worn through or swollen by steam, a lost link between the keypad and the board, or a board that failed its own check after a surge. A breaker reset now and then clears a glitch; a stuck key or a code that comes straight back points to the keypad or the board.

Usually leads to

Microwave control board and touchpad repair

Shows up as

Microwave Touchpad Ignores Key PressesMicrowave Display Dark, Dim or ScrambledMicrowave Won't Turn On at AllWhat a Microwave Error Code Is Telling You

The microwave has noticed trouble with the power reaching it: an outage or a brownout that interrupted a cycle, a voltage too low for the magnetron to start, or a supply that dipped when something else on the circuit switched on. As often as not the cause is the circuit, the outlet in the cabinet above or the breaker rather than the unit; a main fuse that blows again after a reset points inside, where only a technician goes.

Usually leads to

Microwave diagnostic visit

Shows up as

Microwave Won't Turn On at AllMicrowave Trips the Breaker or Blows a FuseMicrowave Display Dark, Dim or ScrambledWhat a Microwave Error Code Is Telling You