Check engine stayed on. Replaced Oxygen Sensor and replaced battery. Check Eingine light stayed off for a few weeks and now comes back on, intermittently. The car runs very well and I cannot detect any apparent problems. Detached battery cables for about 4 hours, but after hooking up, the light came back on. Also had a tuneup when the Oxygen Sensor was installed. Getting good gas mileage and does not use any oil between changes.
Any help or ideas appreciated!