p0012 error >> valve replacement 2011 prius?

Check engine light came on. Just over 100,000 miles. Car running fine, no new noises or rough running or lack of power. Wife took to get oil changed next day. Dealer diagnosed as a sticking valve. Personally I would have cleared it and seen if it reoccurred but dealer already special ordered valve. Searching on the p0012 code I see nothing like this, any others out there with same symptoms?

 

My OBDII reader didn't specify. Dealer ordered "control valve" for $238 + tax. Doesn't mention labor but I'm sure that would be over $100. Direct quote from invoice: "if control valve doesn't fix check engine light concern, camshaft VVTI gear would need to be replaced. (19.0) $3045 after tax)

They did clear the light on the visit, but not the code. Light hasn't come back on after over a week of over 300 miles of use. I wonder what a rebuilt ICE would run, doubt it would be too much more than $3000.