Kenmore Elite Frontload Washer not working

My kenmore elite washer model number 11045091400 works and sometimes it doesn't. When it works, you hear the door lock click and it runs. When it doesn't work, the DLF code comes on. We've tried changing the door lock system, but it doesn't seem to solve the problem. Also, when it does decide to work after not working after a while, it seems to run fine for a few days and then the problem occurs again.