If you're like me and you bought a Galaxy Note 9 on eBay or another used marketplace for a really good price, you may have found that your S-Pen will not connect to the phone. And because the S-Pen won't connect to the phone, many of the enhanced fatures, which are known as the "Air actions", don't work because they depend on Bluetooth to function. The original S-Pen for the Note 9 has a built in battery and Bluetooth transceiver which enables this; fake pens don't have Bluetooth.

The seller I purchased my phone from made it seem like the phone I purchased had an original S-Pen. But when my S-Pen wouldn't connect to the phone no matter what I tried, I became very frustrated. I tried all kinds of solutions for this problem posted all over the web. 

I eventually suspected that my S-Pen was not a genuine OEM S-Pen and it was just a cheap knockoff. 

The cheap knockoff S-Pens do work really good for writing and drawing. They just don't have Bluetooth so you can't use them for any of the remote control features that the Galaxy Note 9 provides such as the ability to use the S-Pen as a remote shutter control, or to use the pen to control music playback.

I contacted the seller of my Note 9 about the S-Pen not connecting and I mentioned to him that I didn't think I received an OEM S-Pen. He insisted that he gave me an original pen, but I insisted that I didn't believe so. After some back and forth messaging, he agreed to send me out a replacement S-Pen. 

And once I popped the replacement S-Pen into my phone, I was able to connect the S-Pen to the Note 9 without any problem. And that confirmed my suspicion that the pen the seller sent me was not a real S-Pen. 

Keep in mind though, if you don't require the Bluetooth enabled features of the S-Pen, a knockoff S-Pen works fine for drawing and writing in my opinion. The one I have has palm rejection and pressure sensitivity just like an OEM pen. You can find cheap replacement S-Pens without Bluetooth on Amazon like this one

Differences between real S-Pen and fake S-Pens

If your S-Pen isn't connecting to your Note 9 and you suspect that it might not be a genuine pen, you can see if you notice these differences I've found between my real Note 9 S-Pen and my fake S-Pen.

Button Size

I noticed that my fake Note 9 S-Pen (bottom) has a larger side button. The larger button is easier for my finger to find. 

Color and Font of "Samsung" text

The "Samsung" text at the end of the pen appears to be a different font and color. The font is bolder on the fake S-Pen (bottom).

OEM S-Pen has a 12 digit serial number

The Genuine Note 9 S-Pen (top) has a 12 digit serial number near the "eraser" end of the pen. 

Only a real S-Pen has Bluetooth, but fake S-Pens without Bluetooth are fine for writing and Drawing

So those are the differences I've spotted between my real Note 9 S-Pen and the fake one. There's nothing bad about the fake one, and like I said, I much prefer the larger side button it has. 

But if you want your S-Pen to connect to your Note 9 and be able to do any of the Bluetooth enabled features like using the S-Pen as a camera remote, then the non-official S-pens can't do that. At least I haven't seen any for sale that advertise that they can.