Exhaust gas oxygen (HEGO) sensor (2.0 litre DOHC/1.6 & 1.8 litre (R6A type) CVH) - removal and refitting

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
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.

    See also:

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    Cold weather precautions
    The functional operation of some components and systems can be affected at temperatures below -30°C (-22°F). ...