2006 Honda oddyssey- trouble code

I am working on a 2006 honda odyssey with a P2646 code- It has 353,00, miles and i have been doing the service work on it for a year or so. The owner will run over the mileage by 1 or 2000 miles for an oil change most of the time and I use a conventional 5w20 oil when i change it. I have used a 5w30 during the summer months a couple of times but I stick with the 5w20 havoline— The check engine light came on along with the VSA light- I check a few things on what causes a p2646 . The oil level was a little low but the low level warning light was not blinking—so i put some engine cleaner in the motor and let her drive it for about two weeks/ then i went back and changed the oil- It had not been that long since i had changed it the last time- maybe 1,500 miles but I put new oil and filter in it. after about 5 miles the code came back on— I checked the oil level and it is good- at the top of the full level– and not sure what to do next- I can change out the VTEC spool valve assembly- or just the sensor on the assembly—– I have a 2004 accord- 2.4 and I have removed the screen and cleaned it and the vtec solenoid and cleaned it several times and it runs perfectly- my accord has 520,000 miles on it—– the solenoid runs about $300 on amazon- Just would like some feedback about other things that could get the cel light out- I thought just changing the oil and adding some motor treatment might help if it was a sludge issue- it said on the code- rocker arm stuck closed?? So give me some ideas——–Thanks