Check Engine light spastic

My check engine light comes on every once in a while when I start the Jeep. It isn't running funny and it starts up fine.

I have a computer that hooks up to the Jeep and reads the codes. It reads 0 which means it didn't throw a code.

I erase the code and it comes back a few weeks later.

The weird thing is that when this happens....if I open the drivers door the "open trunk" light comes on.