Q: How to remove and replace the oxygen sensor in a Buick Skylark,Oldsmobile Omega and Pontiac Phoenix?
A: In L4 engines, the oxygen sensor is a screw-in one located at the exhaust manifold and in V6 engines, it is on the exhaust pipe. For this reason, it is harder to unscrew the sensor when the engine is cold and it would be better if you did it while the engine is operating. In that case, jack up the front of the vehicle and rest it on jack stands to create enough room for your work. On L4 models, extract air cleaner. Oxygen sensor electrical connector should be removed by detaching its terminals. Apply a penetrating oil to the threads of the oxygen sensor during installation ensuring that it penetrates for approximately 5 minutes. Unscrew and remove carefully. Be careful not to damage threads in exhaust manifold/pipe while removing it. Before installing new sensor, coat its threads thoroughly with an anti-seize compound then install it properly. Torque carefully to 30 ft-lb (4.1 m-kg). Reconnect electrical connector to sensor itself as before mentioned. After replacing oxygen sensor reinstall air cleaner on L4 models and lower car on V6models to ground level.When replacing an oxygen sensor, always reset 'sensor' light on dash board panel.