Controlpanel flashes f 3

You have a faulty keypad. You could probably special order this part from a local appliance parts supply store for 50-60$ or purchase a new microwave.

lectric-Gas Oven-Ranges-Stoves Fault Codes:

GE-Hotpoint-RCA
Oven Fault Codes:

F0 & F1 Failed Thermistor Control Replace ERC
F2 Oven Temp Exceeds 590 with unlocked door High resistance in Sensor, likely a bad sensor
F3 Open Sensor circuit Open (blown) sensor fuse or bad Sensor
F4 Shorted wire or Sensor locate short and correct it
F7-A Function pad button stuck Clean and unstick
F7-B Bad Clock Replace Clock
F8 Electrical component failure Replace ERC
F9 Program with door circuit Check wiring

All fault codes for other members reading this post.

Generic Fault Codes:
Fault Code Interpretation Components To Check
F-1 Communication error between touch pad and ERC (clock)
Replace the touch pad or clock.
F-2 Oven temperature sensed by electronic control Replace the clock/relay board
F-3 Open oven sensor or harness. Replace the oven sensor
F-4 Shorted oven sensor or harness Replace the oven sensor
F-5 Power to element relay disabled in cook mode Replace the clock/relay board
F-7 Shorted touch pad key sensed for 32 secs. Replace the touch pad/control panel
F-8 Shorted meat probe Replace the probe jack.
F-9 Door lock safety circuit on ERC sensed Replace the door latch assembly
F-C or F-0 Communication error between boards Replace the relay board.

Frigidaire-Westinghouse-Tappan-Gibson
Oven Fault Codes:
F0 & F1 EOC failure Replace EOC
F2 Oven over heat Defective Sensor or EOC
F3 Oven Sensor Open Replace Sensor
F4 Shorted wire or Sensor locate short and correct it
F5 EOC failure Replace EOC
F6 EOC failure Replace EOC
F7 EOC failure Replace EOC

Maytag-Maycop-Magic Chef-Jennair-Admiral
Oven Fault Codes:
F0 Function key shorted or stuck button Clean and unstick button or replace Touch Pad or Clock
F1 Defective Touch Pad or Membrane Replace Touch Pad or Membrane
F2 Oven over heat defective Relay Board or (if present) or defective Sensor
F3 Oven Sensor Open Replace Sensor
F4 Shorted wire or Sensor locate short and correct it or replace Sensor
F5 Hardware, safety circuits disagree Replace Clock
F6 Missing AC (power) signal Check for proper voltage (plug, breaker, etc.)
F7 Function key shorted or stuck button Clean and unstick button or replace Touch Pad or Clock
F8 A/D Warning Replace Clock
F9 Door Lock Warning Check door lock circuit or Replace Clock

Amana & Caloric Oven Fault Codes:
F0 No Safety Signal Replace adapter board
F1 No Safety Signal Replace ERC
F2 Oven over heat Replace defective Sensor
F3 Oven Sensor Open Replace Sensor
F4 Shorted wire or Sensor locate short and correct it or replace Sensor
F7 Shorted Touch Panel Replace Glass Panel
F9 Door Latch Error Check latch
FF Lock Error Check switch and motor

ERC III - Relay boards....boards having push button controls:
F0 Shorted Push Pad Replace Push Pad
F1 Defective ERC Replace ERC
F2 Oven over heat Replace defective Sensor
F3 Oven Sensor Open Check/Replace Sensor
F4 Shorted wire or Sensor locate short and correct it or replace Sensor
F5 Defective ERC Replace ERC
F6 Defective ERC Replace ERC
F7 Shorted or sticking button Clean button or replace touch pad
F8 Defective ERC Replace ERC
F9 Door Latch Error Check latch

Whirlpool-KitchenAid-Roper Appliances: Oven Fault Codes:
>>Exception Note:<<
Chart below does not apply to Whirlpool Models using the "Y" line in the products model numbers. Applies to models using 4 digit displays only.

F0-E0 Analog to Digital failure
Disconnect panel for 30 seconds
Should the above error re-appear, replacement of the control is required.
F1-E1 Defective ERC Replace ERC
F2-E0 Shorted Keypad Replace Keypad
F3-E0 Sensor or Sensor Fuse Open Replace Sensor or Fuse
F3-E1 Shorted wire or Sensor locate short and correct it or replace Sensor
F3-E2 Oven over heat Replace Sensor
F3-E3 Cleaning Temp over heat Replace Sensor
F5-E0 Door Error Check Door
F5-E1 Door Latch Check Latch
F5-E2 Door Switch Check Switch

Below applies only to the two digit dispaly models for the brands above.
F0 Defective ERC Replace ERC
F1 Defective ERC Replace ERC
F2 Oven over heat Replace defective Sensor
F3 Oven Sensor Open Check/Replace Sensor
F4 Shorted wire or Sensor locate short and correct it or replace Sensor
F5 Defective ERC Replace ERC
F6 Problem with time keeping circuit Reset Time or cooking operation and check for proper ground.
F7 Shorted or sticking button Clean button or replace ERC
F8 Defective ERC Replace ERC
F9 Door Latch Error Check latch and latch circuit