Canon lens.

Hi, my name is David, I have a Canon 24-105 f4 L IS USM Lens, just lately I have been getting a "lens error clean the contacts on the lens".
After I clean the contacts the lens works ok for a while, then it shows the error again. Also when I turn the camera off it seems to work again.
The camera is a 5d mark 2.
Anybody else know of this problem and how to fix it?
Thanks

Did you clean the contacts on the body as well as those on the lens? It could also be something inside the lens where communication is lost, a loose com ribbon cable perhaps.

Welcome to the forum. Since almost all threds here are about Canon lensees, a more descriptive title might help in the future. Try cleaning the lens contacts carefully with a pencil eraser.

Is it a new copy of the lens or an old copy?

Hopefully it is just the contacts, but one of the internal ribbon cables of this lens has been known to go bad. Here's a link.

Err 01?

Check all lenses you have on the body, if there's a theme running then it's most likely your body contacts.

I had the same issue with my 7D around 6 weeks ago. Threw this error up every time. Took it to my local camera shop and it was sent to Canon.

Came back with all contacts replaced, firmware update, thorough in-and-out clean and something else that I've forgotten, for a very reasonable fee. Guaranteed for 6 months.

Good luck.

Thanks for all the messages, 1st time on forum and learned a lot already.