What does P2646 mean and is necessary to stop driving 2011 TL?

 

https://www.autocodes.com/p2646_acura.html
Rocker arm oil pressure VTEC sensor. My wife's pilot had the same error code and it turned out to be a loose connection of the Vtec solenoid on the rear Bank of cylinders. In her case, the engine went into limp mode which prevented us from going over about 15 miles an hour. I would definitely have it looked at and fixed before you drove much.

 

,Did you check your oil level?. If you didn't ,go ahead and check it, you might be surprised.