I used to own a 99 Dodge Avenger Sport and I am looking to buy a 99 Dodge Avenger ES. I found a local car ad that states everthing works on the car and that all it needs is an O2 sensor.
My question is how does needing an O2 sensor effect the car's drivability? Acording to the seller, it is only a 60 dollar part. I'm wondering why the seller just doesn't replace it, and THEN sell the car. Is it possible that a "bad O2 sensor" could be an excuse to try to cover up a bigger problem and if so, WHAT?

 

yes the sensor is $60 or so it can effect gas mileage (poor) but not seen major otherissues from it ... If the person is not mechanically inclined the mechanic could charge $150/$250
for diagnostic/replacement