Simple Temporary Fix: Use a hair dryer on the sensor.
Detailed Answer:
I have had the E-11 error several times and had to turn the breaker off to stop the beeping. Usually the next day the error will have cleared.
The error seems to occur at the most inconvenient moment. After researching that it is the humidity sensor, I went ahead and ordered a replacement, figuring I would install the new sensor the next time the error occurred.
Well, the next time the E-11 error popped up, it was right during meal preparation time, and I couldn’t take the microwave down at that moment to replace it. Knowing that it was the sensor, slowly going bad, and not water pouring into the microwave from somewhere, I turned the breaker off. I used a hair dryer on the sensor and it cleared the error quickly.
I put the hair dryer on low heat and aimed it at the holes on the inside back left corner ceiling of the cooking chamber. Holding the hair dryer on low, I moved it back and forth, about 3-4 inches from the holes that are below the sensor for about 30 seconds. See the photo. It doesn’t have to get very hot, mostly warm air on the sensor will dry it out.
After letting it cool off for a couple of minutes, I turned the breaker back on, reset the time and I was good to go.
The correct fix is to replace the humidity sensor, but if it’s not convenient, the hair dryer trick just might temporarily help.