Vsc Maintence Issue

[banjofan]

I have a 1998 Lexus LS 400 with 222,800 miles. I am the 2nd owner and have driven it since 82,000 miles. It has given me only minimal problems. I took it in to a local mechanic to have a brake job done, and also to fix some oil leaks. While it was in the shop, I asked him to also change the spark plugs and change the timing belt. When I got it back, the car drove great for about thirty minutes then the check engine light came on, followed in seconds by the VSC Off light, then the Check VSC light. I took the car to Autozone, and got the following codes:

P1656; P1346; P1325; and P0340

I've read a lot of posts on this site, and suspect the oil control valve as being the place to start. Any suggestions of the possible problems before I start working on the vehicle?