my smart key will unlock if i press the button but it has stopped auto detecting when i walk up to the car, usually it will automatically unlock the door when i get close, it stopped last week but battery is good on alarm.

 

Have you tried using it on another door? Maybe the lock actuator broke.

 

I would change the battery. Do you have a second key fob? Both doing it? Or just one?

I changed the battery in both key fobs and sporadic issues went away.

 

"...automatically unlock the door when i get close..." Are you sure you remember this correctly? I don't think the SMART key can actually do that.

Normally, you have to grab the handle (touching the sensors on the back of the handle) to unlock the door. Refer to pages from the Owner's Manual below...

 

^^^^^^ This.

It only unlocks once you put you grip the handle. What should be happening is that as you approach the car, the lights illuminate, both interior and side mirrors. Is that happening?

Are you still able to start the car without putting the key in the ignition? Sometimes my car stops detecting my presence so I have the issue your are having plus the inability to start the car without putting the key in the ignition. It's always because I somehow accidentally pressed the button under the dash and deactivated the smart system. I would check that. It happens to me every so often.