I recently installed a new O2 sensor, however the distance between the connector and the sensor is much longer than needed. (about 18 inches). I coiled the wire, tied it off under the car and everything is working fine. Now, of course, second thoughts....should I be worried? Another related question. Is the only difference between the pre and post cat sensors the distance between the connector and the sensor. Its too embarassing of a story, but in addition to having a sensor that is too long, I also have an extra one and thought I could use it for the post cat.
You didn't say what kind of car you have - that might be pertinent. I would think the connectors and wires would show any visible difference, but, who knows, maybe there's different internal electronic specs or somesuch. If your car's using a typical narrow-band sensor, some extra wire length probably isn't a big deal; if not and it's a wideband sensor (which I'm guessing is unlikely), correct lead length _might_ be important. If it was an oem part, you'd think you'd have the same lead length as the original sensor.
I did an O2 sensor on another car where I work and it had a much too long wire too, I did the same thing you did and the customer hasn't come back yet seems strange though, what brand was it? maybe the cheaper autoparts store brands just have some design defects
