Oldsmobile/Buick Repair: check engine light 94 buick lesabre, oxygen sensor, buick lesabre

Question
Dear Sir,
I have a 94 LeSabre with the 3800 V6.  It has 91000 miles on it.  I had to replace the catalytic converter on it about a month ago and soon thereafter the check engine light would come on after driving 20 minutes or so.  If I turn the car off and restart it, the light goes off again for a while.  In your expert opinion do you think this is the oxygen sensor? If so, where is the oxygen sensor and is it difficult to replace by myself?  Thanks again, I appreciate it.

Answer
Hello Dave,
The only way I would think replacing the cat would cause an oxygen sensor light, is if they damaged the O2 sensor wires, or just didn't connect it.
The sensor is in the exhaust pipe, in front of the cat.

I would go to a parts house where they read the codes for you, and see what codes, if any, are stored.

Keep in mind....if you have an O2 code, it doesent necessarily mean the sensor is bad. it could be correctly reading a rich or lean condition.

A real rich condition could be what caused you to need a new converter in the first place. Raw fuel in the exhaust can melt down a converter.

Van