Locate the Oxygen Sensors

• 1). Warm up the engine to operating temperature. In most cases, you need to warm up the engine to ease the threads--on the sensor mounting bolts or the sensor itself--off the exhaust manifold or pipe. Trying to force loose a hard-to-remove sensor with the exhaust system bellow 120 degrees F (48 C) may damage the threads and result in costly repairs.
  
  
• 2). Open the hood and locate the oxygen sensor or sensors you want to replace. The sensor has a cylindrical body and is the size of a spark plug. Depending on your particular model, you may find the sensor mounted on the exhaust manifold or the exhaust pipe connected to the manifold. The upstream sensor is located right before the catalytic converter and the downstream sensor right after the catalytic converter.
  
  
• 3). Disconnect the black, negative battery cable.
  
  
• 4). Raise the front of the vehicle using a floor jack and safely support it on two jack stands if necessary.
  
  

Remove the Old Oxygen Sensor

• 1). Unplug the sensor's electrical connector from its harness.
  
  
• 2). Unscrew the two mounting bolts using a wrench or ratchet and socket, if you have a flange-type sensor. If you have a screw-in type sensor, remove it with a box-end wrench or a ratchet and oxygen sensor socket.
  
  
• 3). Remove the oxygen sensor gasket from the exhaust pipe mounting base if you have a flange-type sensor.
  
  
• 4). Remove the sensor from the vehicle.
  
  

Install a New Oxygen Sensor

• 1). Apply a light coat of anti-seize compound to the threads of the two sensor mounting bolts if you have the flange type or to the threads on the body of the sensor if you have the screw-in type. Make sure the compound does not get to the tip of the sensor.
  
  
• 2). Set the new sensor in place and new gasket if required.
  
  
• 3). Start the two mounting bolts by hand if you have the flange-type sensor, or screw the sensor in place by hand, if you have the screw-in type.
  
  
• 4). Tighten the mounting bolts or the sensor to the exhaust pipe.
  
  
• 5). Plug the sensor electrical connector.
  
  
• 6). Remove and install the other sensor, if necessary, following the steps on the last two sections.
  
  
• 7). Lower the vehicle.
  
  
• 8). Connect the black, negative battery cable.