Chevrolet Chevette/1000 1976-1988 Repair Guide

Oxygen Sensor

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OPERATION





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Fig. Fig. 1The oxygen sensor (which resembles a spark plug) is threaded into the exhaust manifold

An oxygen sensor is used on all models. The sensor protrudes into the exhaust stream and monitors the oxygen content of the exhaust gases. The difference between the oxygen content of the exhaust gases and that of the outside air generates a voltage signal to the ECM. The ECM monitors this voltage and, depending upon the value of the signal received, issues a command to adjust for a rich or a lean condition.

No attempt should ever be made to measure the voltage output of the sensor. The current drain of any conventional voltmeter would be such that it would permanently damage the sensor. No jumpers, test leads or any other electrical connections should ever be made to the sensor. Use these tools ONLY on the ECM side of the wiring harness connector AFTER disconnecting it from the sensor.

REMOVAL & INSTALLATION





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Fig. Fig. 2The oxygen sensor, which resembles a spark plug, is threaded into the exhaust manifold

The oxygen sensor must be replaced every 30,000 miles (48,000 km.). The sensor may be difficult to remove when the engine temperature is below 120°F (49°C). Excessive removal force may damage the threads in the exhaust manifold or pipe; follow the removal procedure carefully.

  1. Disconnect the negative battery cable.
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  3. Locate the oxygen sensor. It protrudes from the exhaust manifold (and looks somewhat like a spark plug). If necessary, raise the car for access.
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  5. Detach the electrical connector from the oxygen sensor.
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WARNING
The oxygen sensor uses a permanently attached pigtail and connector. Do not remove the pigtail from the oxygen sensor.

  1. The oxygen sensor may be difficult to remove when the engine temperature is below 120°F. Spray a commercial heat riser solvent onto the sensor threads and allow it to soak in for at least five minutes.
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WARNING
Excessive force may damage the threads in the exhaust manifold. Also care so the that the in-line electrical connector and the louvered end are free of grease, dirt and other contaminants.

  1. Carefully unscrew and remove the sensor.
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To install:

  1. First coat the new sensor's threads with G.M. anti-seize compound No. 5613695 or the equivalent. This is not a conventional anti-seize paste. The use of a regular compound may electrically insulate the sensor, rendering it inoperative. You must coat the threads with an electrically conductive anti-seize compound.
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  3. Installation torque is 30 ft. lbs. (42 Nm.). Do not overtighten.
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  5. Reconnect the electrical connector. Be careful not to damage the electrical pigtail. Check the sensor boot for proper fit and installation.
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