Problem getting engine check light code
 

I’m trying to pull check engine light codes from my S5. I’m getting 10mpg with everything pretty much stock. My engine check light goes away every time I step on the gas which is really annoying. I replaced the O2 sensor and that didn’t do anything.

http://www.1300cc.com/howto/how2/codes.html

Here is the guide I’m trying to follow but I’m getting stuck on the first step which is grounding the wire. When I turn the car on the engine check light just stays on. I think I’m missing something really simple here. What kind of wire should I be using? Right now I’m using a thin copper wire which doesn’t seem to be doing the trick.

anyone?