I can't find anything that says they should be related, but it seems that they are. There must be a default mode that kicks VSA off with certain Trouble Codes.
At any rate, I replaced the Oil Pressure Switch. It was just under $60 from autozone. The procedure was fairly easy when you know where to look and can get at it. There is another part that comes up with Oil Pressure Switch when autozone searches. It is about 8 bucks. This isn't the proper switch for this procedure.
tools needed: 10mm socket, 22mm Socket,(Needle nose pliers might be helpful)
location: The Oil Pressure Switch and VTEC Solenoid are located directly above the oil filter and are accessible from the engine bay.
1. Use the 10mm socket to remove a bracket holding a hose. Yo umay be able to do this job with that hose in the way, but 30 seconds will make your job way easier.
2. Use the pliers (or your fingers) to unplug the wires from the Switch. There are two plugs back in that vicinity, It will be the one on your right (closer to driver's side)
3. Use the 22mm socket to remove the switch. There is an o-ring that should probably be replaced, do not forget to use that when installing the new switch.
4. Reverse procedure with the new switch.
(easy, wasn't it?)
NOW, my engine was not fixed by this procedure, so I decided that I should clean out the filter that I kept reading about. My advice is to try the following procedure FIRST if you ever get the p2646 code. You might save yourself 60 bucks.
Tools/supplies needed: 10mm Socket, carb cleaner OR new screen
Now, this part was slightly more difficult to find a procedure on, but is super easy when you know what you are doing. That's why I'm posting it here.
1. There are 3 screws on the "block" that the solenoid and the oil pressure switch are on. They are located on the back side of it (aimed towards the engine) They all may be removed with a 10mm socket.
2. YOU MAY leave the entire unit plugged in while you do this, or you may remove the plugs and the wire holders that are attached to this unit (PITA). At this point you need to either pull the screen off of the engine block, or off of this part you have dangling in the back.
3. Either replace this screen (which seems to serve as a gasket, as well) or you may clean the screen out. I found a grainy layer of oil on mine, this seemed to be necessary. I guess they put a screen there on purpose, so it was doing its job.
4. Reverse procedure with new/cleaned screen.
5. If you haven't done it recently, now would be an appropriate time to change your oil and filter.
In a clean garage, with your tools handy, this entire procedure could be done in 30 minutes. It took me an hour, but I had to keep coming back to the FSM and the Internet to figure out what the heck to do.
If your codes come back after these repairs (in spite of erasing them) then double check the connectors. I was getting a code and decided to check my connectors, they looked ok, but after I unplugged stuff and replugged it in, making sure to take extra care that they were firmly seated, the codes haven't returned. Let's hope this post isn't premature and that the problem is solved.