Ok I have a 2003 Honda Accord and about a week ago the CEL came on the ecu keep going into and I call "limp mode". Car would rev over 2500 rpms and just ran like crap. So i had the motor scanned and they said it was bank 2 o2 sensor. So I changed it and it was obvious that the other was bad and went ahead and changed the plugs as well w/ were horrible looking. So after that the motor ran good for about 15min and than bam the CEL kicked back on. So I turned around and had it scanned. Its now pulling error code:

Code 2646: A Rocker Arm Actuator System Stuck Off

What the hell is that and how the hell do I fix it? I'm new to the K-series motors so please someone help me out here...

 

Perhaps the code was read with a generic type scan tool. The Honda listing shows the actual fault is the V-tec oil pressure switch.
Often times low oil level can cause this problem as well as a faulty pressure switch.

 

A lot of people have been having primary o2 sensor's go bad, causing the same thing you had with the motor running like crap (rich) above 2500 rpms. Although, never heard of the second problem coming after. Usually a replaced o2 sensor does the trick.

 

if its the primary o2, it is most likely throwing the ecu in and out of "limp mode" causing it to run like crap sometimes. I had the same problem with my 6 gen.