Need some help - Check Engine Light - Trying to Sell Car

Of course, like everything the first day I put my car in the newspaper the check engine light comes on. It happens when I am on the highway, about 10 minutes into driving, going about 70. Comes on for about 10 seconds then goes off, 5 minutes later comes on for 10 seconds and goes off. Did it about 5 times.

I pulled the codes and got:
542
543
116
314


Any help is appreciated, I have people coming to test drive my car tommorow and I'm afraid that even if I tell them that the light doesn't affect the cars driving (which is doesn't) they will think I'm lying and not buy the car.

Thanks in advance