The 1996 Buick Regal features two oxygen sensors (also known as O2 sensors) in the exhaust system. One is located upstream in the exhaust manifold and monitors the fuel-to-air ratio, since combustible engines require oxygenated air to operate properly while lowering emissions. The downstream sensor is located near the catalytic converter and monitors the efficiency of the catalyst as it filters out pollutants and controls the amount of harmful exhaust emissions. Replacing either O2 sensor calls for the same procedure; the only difference is the location and the part number for the sensor.
Tools Used: Tools, 2 car ramps (for downstream sensor only), Mechanics’ gloves, Mechanics’ long-sleeved shirt, Penetrating lubricant, 22-mm box-end wrench, 3/8-inch drive ratchet with 3/8-inch drive 22-mm oxygen sensor socket, Direct-fit replacement oxygen sensor(s), GM anti-seize compound No. 5613695 or the equivalent
Remove Oxygen Sensor
Warm the engine up for five minutes if it’s cold. Put on mechanics’ long-sleeved shirt and gloves to help protect yourself from engine burns. Open the hood and locate the front oxygen sensor placed in the exhaust manifold at the front bottom of the engine compartment.
Spray a liberal amount of penetrating lubricant on the threads and manifold connection of the sensor. Allow five minutes for the lubricant to soak in. Follow the wire harness connection to the dual plugs. Disconnect the dual plugs from one another.
Use the ratchet and 22-mm slotted oxygen sensor socket to remove the upstream sensor. Place the wire harness of the sensor into the slot of the socket, then attach the ratchet to the socket. Turn the sensor counterclockwise to remove it from the manifold. If necessary, start the engine up and spray the sensor threads with lubricant again. (Starting the engine will expand the metal of the exhaust pipe and allow easier removal of the sensor.)