GMC Repair: 1997 jimmy Check engine light, o2 sensor, hiway

Question
I recently purchased a 97 jimmy when I looked at it at the dealership the check engine light was on I was told this was due to a O2 sensor which they replaced. I was doing some Hiway driving today and I noticed my RPM's would randomly drop 200-300 rpm. I stoppped to get gas and as I left the station the Check engine light came on and the rpm drop stopped (ran better after light came on)At this point my sister informed me she had run out of gas earlier today (coasted into the station) could any of this explain the engine light, or the rpm drop? and what would I need to do to fix it?


Answer
When the check engine light illuminates the computer goes into a DEFAULT RUNNING MODE. You need to get the check engine lght diagnosed to determine WHY it is illuminated.

If they changed the o2 sensor the light should NOT be ON.

It is possible that the light is ON due to your wife running out of gas.

If the vehicle seems to be running OK, after a day or two of driving the light should go OUT.


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