The guy at AutoZone just told me my o2 sensor was bad. The Check Engine light has been on for about 3 weeks now. I can get one for $61.99 and would like to replace it myself. My questions are:

1. How hard is it? I can see it and should be able to get a wrench or socket around it, but I have read that it can be VERY hard to remove. Has anyone done this with success?

2. Will my Check Engine Light go out by itself or is there a procedure I would have to do to reset the ECU? I found this (below) in another thread but it really doesn't say how to reset it. What is the "Procedure"?

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The '91 - '93('93.5) G20's were running OBD-I. They can be reset by the legendary battery disconnection.

The '94-'96 OBD-II's will not fully reset the ECU just by disconnecting the battery for a period of time. You have to follow the simple 10 min or less procedure to reset the ECU correctly at the ECU screw.
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Brandon
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Thanks in advance, I have been lurking around here for a few months now and really appreiciate the information.

G20John

Sorry this is a 96 G20 about 74,000 miles.

G20John

Replacing the O2 sensor is easy. You'll need a large open ended wrench. Around 16 or 18mm if I remember correctly. Make sure to buy some anti-seize compound and spread it on the threads of the new sensore before installing, be sure not to get any on the sensor or you could ruin it.
I don't have the procedure for resetting the sensor in front of me.
Try a search on the forum for help with that.
Good luck.