Nikon D40 lens having trouble focusing?

My Nikon D40 camera has been having trouble focusing. I use the Auto-focus option, and sometimes it doesn't focus, and makes this, clicking sound. It sometimes even says that the lense is not attatched. So I reattatch it and it works(sometimes). Does the interior just need to be cleaned or is it time for a new lense?

I would first call Nikon and ask them. 800. NIKON-UX

Having a lens auto focus fail is very unusual.

You may have dirty contacts on either the lens or camera. Make sure that they are clean and are making good contact.

Cleaning the interior of your camera will do nothing except maybe introduce dust into your sensor. Not a good thing

Look on page 108 for options when troubleshooting the camera.

As you will see, pages 14, 23, 24 and 26 discuss focusing the lens.

If the problem exists only in low light, then you need to assure that the auto focus assist lamp is turned on, page 23

Sounds like time to go to a camera shop that can clean your camera, they will take in your camera and give the contacts a good clean. Also bring in the lenses you have troubles with. You will get them back all cleaned up and there should be no more troubles.

If troubles keep on existing after a good clean then well… Lets just first go through this shall we. Cleaning lenses and cameras will cost some money but not to much. And it is worth it even for an older camera like you have.

Nikon's kit lenses, the 18-55 and 18-105 have a bad contact design on the lenses. I'm surprised you haven't come across this before. I have experienced this on a few systems. You can gently clean the contacts if it's really bad. Rotating the lens back and forth a few times (don't use force!) without releasing the lens lock is usually enough to fix this issue for a couple days.