How to fix error 01 "communication between the camera and lens is faulty" on eos rebel t2i

[jrhoffman75]

Remove lens. Using a cloth gently wipe the gold contacts on the lens and the camera. Reinstall lens.

If you have access to a second lens and/or camera try different lens on your camera to see which component has problem, or install your lens on a different camera.

[millaman_adam]

The problem is the lens, not the camera. I tried using my 18-55mm lens and it worked perfectly fine. 

[ebiggs1]

Unless you have reason to believe dirty contacts, cleaning them rarely helps.  But one reason would be if you left the lens on the camera for a long time.  I mean years!  But if you change the lens from time to time, the contacts self clean.

As John Hoffman advises, trying a different lens is in order.  You must know which is faulty.

[TCampbell]

Just inside the lens mounting flange on the camera body you'll see the gold "pins" and these mate with the gold contact plates on the lens side.  

The "pins" are all spring loaded - so they work like button in that you should be able to press on each pin individually and it should spring right back out.

If you've got a pice of grit jamming a pin then it's possible one of the pins is not springing back out to make contact with the lens.  

Check to make sure you don't have a jammed pin.

It's especially helpful if you have a different lens that you can use to determine if this issue is unique to just one lens (in which case it's probably a fault with the lens) or if it happens to every lens (in which case it's the camera body at fault.)

[jrhoffman75]

Check the Canon eStore for refurb lens to compare price vs repair cost.