My Maytag (aka Whirlpool) over the range microwave model number MMV5219DS-1 shows the F1E4 error code, but I have tested every relay on the controller board (7 total) without finding any failures. If I reassemble the controller board back into the microwave it goes back to working again, but over time it will eventually stop working again with the same error code. The last operational period was about 4 months with no problems and then it happened again. I have not found any diagnostic or service information that would help me sort out this problem. Initially I thought the problem was with the controller board, but I am not convinced this is actually true. I also thought that the small outline transistors used to enable the relay switch coils on the controller board might have a cold solder joint, so I reflowed the solder on all of them prior to the last error code occurrence. So obviously this didn't help at all.