Rep Power: 0

I own a 2005 honda civic ex and today it redlines at 4 rpm, drives fine below 4 rpm but as soon as it hits it, it redlines, any idea what it is?

 
Rep Power: 222

Like it won't go above 4k?

 
Rep Power: 367

Redline is around 7k RPM, it's called that because above that there is a red marking in the tachometer.
What you are having is a limp mode, you have some issue in your engine and the ECU is not letting it go above 4k, so it will not destroy engine.
Your check engine light should be on on the dash. Have the engine codes read in autozone or similar.

 
Rep Power: 126

Limp mode, check codes.