GM Cutlass RWD 1970-1987 Repair Guide

Oxygen Sensor


An oxygen sensor is used on all 1980 models built for California and on all 1981 and later models for all 50 states. 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. A failure in the oxygen sensor circuit can cause trouble codes 13, 44 or 45. To test the oxygen sensor, connect a dwell meter on the 6 cylinder scale to the mixture control solenoid dwell terminal. Start and run the engine until it reaches normal operating temperature, then run the engine at fast idle for 1 minute.

Keep hands, hair, clothing, wires or any objects clear of moving engine parts.

Return the engine to idle and note dwell reading. They should be varying between 10 degrees and 50 degrees. If the sensor does not meet these requirements, have the system diagnosed and repaired by a qualified technician.


See Figures 1 and 2

Take care when handling the oxygen sensor. The in-line connector and louvered end must be kept free of grease and other contaminants. Also, avoid using cleaning solvents of any type. Do not drop or roughly handle the oxygen sensor.

  1. Disconnect the negative battery cable.
  3. Disengage the sensor's electrical connection.
  5. Using the proper size socket or wrench carefully loosen the oxygen sensor. The sensor may be hard to remove when the engine temperature is below 128°F (48°C). Excessive force may damage threads in the exhaust manifold or exhaust pipe. If removing sensor while the engine is warm, wear protection such as heavy gloves and long sleeves to prevent injury and burns.

To install:
  1. Install sensor and torque to 30 ft. lbs. (41 Nm).
  3. Connect the electrical connector.
  5. Connect the negative battery cable.

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Fig. Fig. 1: Oxygen sensor

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Fig. Fig. 2: The oxygen sensor is threaded into the exhaust manifold or pipe