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How do I change the 02 sensors on a 2008 Saturn Astra?

Answers from the Automotive Experts

Amanda J. Pierce, MBA You have heated oxygen sensors (HO2S) 1&2. Disconnect neg. cable of battery, loosen the bracket nut on harness mounted transmission housing, remove & install O2S

Gelina Aquilina, Service Advisor / Mechanic at The heated oxygen sensors each use a permanently attached pigtail and connector. Do not remove the pigtail from the heated oxygen sensor. Damage or removal of the pigtail or the connector affects proper operation of the heated oxygen sensor. Handle the oxygen sensor carefully. Do not drop the oxygen sensor. Keep the in-line connector and the louvered end free of grease, dirt, or other contaminants. Do not use cleaning solvents of any type. Do not repair the wiring, the connector, or the terminals. Replace the oxygen sensor if the pigtail wiring, the terminals, or the connector is damaged. Proper oxygen sensor operation requires an external air reference. This external air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, the connectors, or the terminals results in the obstruction of the air reference and degrades the oxygen sensor performance. A dropped oxygen sensor is a bad oxygen sensor. The oxygen sensor may be difficult to remove when the engine temperature is below 48°C (120°F). Excessive force may damage threads in the exhaust manifold or the exhaust pipe. Disconnect the oxygen sensor wiring harness plug (3). Disconnect the wiring harness (2). Remove the oxygen sensor (1) from the front exhaust pipe with SA9603E /KM-6179 . When re-using the oxygen sensor, coat the thread of the oxygen sensor with assembly paste (white). Install the oxygen sensor 2 in the front exhaust pipe using SA9603E /KM-6179 . Tighten to 40 N.m (30 lb ft). Connect the wiring harness plug for the oxygen sensor. Install the wiring harness.

Helaine Kurot, Owner/Technician at 360 Automotive There is a special O2 socket that is used to remove the O2 sensors. The socket should be available at most reputable parts stores. You will be much better off purchasing the 02 sensors from a GM dealer as the vehicle's computer may not like a new aftermarket sensor. The front O2 should be accessible from the engine compartment. The second O2 is after the cat in the exhaust system. Be careful disconnecting the wiring harness. They should have squeeze tabs on them to release. Unplug the sensor before trying to remove it. Also note that when you are installing new sensors the torque spec is only 30 ft-lbs. over tightening will strip out the exhaust pipe.

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