2004 Honda Civic P2647 check engine code

What is your question?

Hi I am getting a p2647 error on my 2004 Honda Civc Ex couple. It is for "Rocker Arm Stuck Open". I have replaced the Oil Pressure Switch located above the oil filer with a Honda OEM part that did not solve the issue. This engine is the D17 and is not equipped with the VTEC Solenoid assembly which I see online of many people who have this code. I am considering flushing the engine since I just bought the car and do not know the past maintenance history. Do you recommend anything I can do?

How long has your 2004 Honda Civic had this problem?

Since I bought it a few weeks ago