Ha-ha-ha.
After cleaning the owner brings the lens to the service (to me, for example), and we repair the broken cable or whatever. I have never seen a case when cleaning helped.
Till now.
the lens was a simple 18-55 is – everybody knows, that the focus feedback cable breaks after a certain time, and then no photos more possible. the owner told me something about problems by shooting, I DIDN’T CHECKED IT, i just rushed on the lens, to change the cable. but it was not bad… oupppps.
after assembling, disassembling it i started to believe, what i have seen: no aperture value on the lcd… at last i observed, that the contacts are pretty oxidized.
i cleaned them – and what a surprize: no failure 🙂
trust canon! trust the error codes! (ok, it was just a joke)
DIGITAL CANON repair blog 
What are You using for cleaning the contact?
What are you use for cleaning the pins?
white spirit, brake cleaner, contact cleaner, rust-remover, phosforic-acid, sand-paper, cutter-knife – depends on the case.
I’m asking, couse I have a brand new EOS 70d, and an old Sigma 400mm F5.6 Apo Macro HSM lens, and in room conditions everything is ok, the lens working correctly at 5.6. But as i going for outside, below 0C, I got the usual ERR01. For me, the connections seems everything is ok.
in this case I rather think, there could be a contact problem (for example a so called cold soldering point, which means a broken soldering connection) on the board of the lens.
try it on another camera.