I have a 2nd Gen MDX and my stock sub repeatedly turns off for 1 or 2 secs at the time when hitting the lowest frequency on a song when the volume is greater than 20 and then comes back on. I checked the wires in the sub connector to see if anything was loose or broken that was getting miscontact with the vibration but I didn't see anything visually wrong.

What could be wrong with my sub? Do you think the amp inside the sub enclosure is loosing it or maybe the sub speaker itself?

 

My guess is the amp if your sub plays all other frequencies and the wires are in place.