Saturn Problems

For a couple of weeks now, Sarah’s “Check Engine” light has been on.  The last time it happened, it went off after about a week, so I had been waiting to see what happened with it.  But since it hasn’t gone off, I decided to run over to Auto Zone and have them hook it up so I can see what’s wrong.  The printout said something about an oxygen sensor being bad, and something about an issue with the thermostat.  I had known there was a potential issue with the thermostat for a while.  When we got her car and were having the problems with the oil leak, the mechanic had said that the housing was cracked and that it would drip coolant, not a lot, just a few drops.  As long as we kept monitoring the level we would be OK.  So now I wonder if that is the case, or if it is something else.  So I guess that now it is time to take it back to the car guy and have him check it out in more detail and tell me what might be wrong now.