Chrysler Full-Size Trucks 1967-1988 Repair Guide

Oxygen (O



The oxygen sensor produces an electrical voltage when exposed to the oxygen present in the exhaust gases. The sensor is usually mounted in the exhaust manifold. On some applications, the sensor is heated internally (with an electric element) for faster/more reliable performance. When there is a large amount of oxygen present (lean mixture), the sensor produces a low voltage. When there is less oxygen present (rich mixture) it produces a higher voltage. By monitoring the oxygen content and converting it to electrical voltage, the sensor acts as a rich-lean switch. The voltage is transmitted to the SMEC, which then signals the power module to trigger the fuel injector. The injector controls fuel mixture.


  1. Disconnect the engine harness wire from the sensor.
  3. Remove the sensor using tool C-4589 or equivalent.

Do NOT pull on the sensor wire. Be careful when working around the sensor, as the exhaust manifold is HOT and can cause severe burns.

  1. Always clean the threads of the exhaust manifold before replacing the sensor. Use an anti-seize compound to lubricate the threads of the new sensor before installation. New sensors are usually packaged with the compound already in place; if this is the case, you not need to apply additional compound.
  3. Torque the sensor to 20 ft. lbs. (27 Nm).