Check engine light 1997 grand am?

My 1997 Ranger check engine light came on. Think I might know why?

• For the past 6 months or so the exhaust has been off of my 1997 Ranger V6 4.0L. The exhaust was taken off from where it connects right behind the passenger side of the cab. I have now put it back on and since then the engine sounds quite grumpy when moving from idle. On my way to work this morning the check engine light went on. I'm guessing it has something to do with the exhaust being put back on and I'm going to go to Autozone to get the code checked out while im on lunch but I just wanted to know if anyone knows what it might be or what I need to do to get rid of the code. I know getting the code read will make things much easier but just throwing this out there. I'm selling my truck this week (hence why I put the exhaust back on) and as you all know, no one wants to buy a car with a Check Engine Light on. Thanks!

• Answer:

  if you had the exhaust off then the computer is now trying to compensate for new parameters-might try taking off battery leads and leave off for 15-20 minutes to let ecm restart--do this before trading