Note: Do not touch the tip of the HEGO sensor as this will drastically shorten its service life.

Note: A new sealing ring should be used on refitting.

Removal
1 Ensure that the engine and the exhaust system are cold.

2 Disconnect the battery negative lead.

3 Apply the handbrake, then jack up the front of the vehicle, and support it securely on axle stands (see “Jacking and Vehicle Support”).

4 Disconnect the sensor wiring plug halves by releasing the locktabs and pulling on the plug halves, not the wiring.

5 Where fitted, slide the heat shield from the sensor (see illustration).

35.5 Sliding the heat shield from the exhaust gas oxygen sensor

6 Unscrew the sensor from the exhaust downpipe, and recover the sealing ring. Do not touch the tip of the sensor if it is to be refitted.

Refitting
7 Commence refitting by ensuring that the sensor threads and the corresponding threads in the downpipe are clean.

8 Refit the sensor using a new sealing ring, and tighten it to the specified torque.

9 Further refitting is a reversal of removal, but on completion start the engine, and check for leaks around the sensor sealing ring.