I just replaced the oxygen sensor on my '89 Maxima SE, and now, I keep getting a check engine light. On the old OEM sensor, the light wasn't coming on at all when I replaced it, but for some reason, the check engine light has come on for the third time in 2 days now.

The oxygen sensor I bought was a Bosch unit, P/N #13388. Both the original sensor and the Bosch sensor has two plugs. The only difference between the two was that the new sensor had four wires coming off of the sensor, while the OEM sensor had three wires, but a fourth wire (which after disassembling the old sensor) seems to be more of some type of wire shield around one of the three other wires.

Has anyone ever had this strange problem where a new oxygen sensor would set off a check engine light but the old sensor wouldn't? I've reset the computer manually three times already, and am very close to try to disconnect the battery, let the car sit overnight to clear everything from the ECM, and trying it fresh the next day.

(If it isn't one problem, it's another ... )