How do you change oxygen sensor on a 2001 Pontiac Aztec?

To change the oxygen sensor on a 2001 Pontiac Aztek, first ensure the engine is cool, then disconnect the negative battery cable. Locate the oxygen sensor, which is usually found on the exhaust manifold or exhaust pipe. Use a wrench or O2 sensor socket to unscrew the old sensor, then install the new sensor by threading it in and tightening it securely. Finally, reconnect the battery and reset any error codes if necessary.