I recently picked up a 2009 Pilot. It was older than I really wanted but, it's in immaculate shape and has <90,000 miles so I went for it. A day after I bought it I started getting the P3400 code. After some research, I found out that this is pretty common and the main reason for it is a faulty oil pressure switch on the rear rocker arm. I ordered the part and replaced it but the code persisted. I also read that low quality oil can make this go off so I changed the oil as well. Still getting the code. I was then informed that the Honda V-Tec engines don't always recognize after market parts and I would need to replace the oil pressure switch with a "Genuine Honda" part. I did that and the code went away for a couple days but now it's back. Does anyone else have this problem? What's the next step? I'm totally at a loss here.