2001 Aurora SES light question

Looking at buying a 2001 Aurora. The SES light is on and I was told that the cause (excuse my stupidness here) is a loose wire that tells the computer something when the car rpm's decrease during HWY driving? I have never owened an Aurora so I dont even know what this guy is talking about. Can anyone elaborate on this or is it BS.

Thanks.

Right, BS, this could be anything, a scan for the code is required.