If you are home and always have your Yorkie directly within your line of sight, tethered to you, or in his playpen, there should be essentially no times of accidents.
And, if when you are not home you have your Yorkie in a playpen, since this is a defined space, pee and poo will be kept to one small area, and hopefully on the pee pads.
This said, if your Yorkie does pee and poo in the house, you'll want to react the right way and clean it in the right way.
If you see your Yorkie starting to pee or poo, interrupt him via a loud hand clap and a firm 'No.' Immediately bring him out, and if you feel that there is no time to walk him out, carry him (grabbing the leash and treats on the way out the door).
If you come across a puddle of pee or a little pile of poo but did not witness it happening, reassess what lead to this in the first place. Were you following the supervision and confinement methods?
Also, do not bother reprimanding; it will do little good and being scolded or yelled at may only serve to make your Yorkie afraid of you.
Both urine and feces leave strong, lingering scents. The enzymes in this waste matter are not washed away with soap and water. So, while you may not smell anything at all, and the spot may look clean once you've taken care of it, it may still be sending out an almost impossible-to-ignore message to your Yorkie that says 'This is the bathroom area'.