should have one heres how to change it it is on exhaust manifold please make sure engine is cooled down before changing.

Disconnect the negative battery cable.
Detach the sensor electrical connector.
Carefully remove the Oxygen (O2) sensor.

Fig. 1: The oxygen sensor is usually mounted on the exhaust manifold - 1988 2.0L (VIN K) engine shown

Fig. 2: A wrench may be used to remove the oxygen sensor

To install:
A special anti-seize compound is used on the O2 sensor threads. This compound is made up of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will remain, making the sensor easier to remove. New or service sensors will already have the compound applied to the threads. If a sensor is removed from the engine, and is to be reinstalled, the threads must have anti-seize compound applied prior to reinstallation.

If reinstalling the old sensor, coat the threads of the sensor with anti-seize compound 5613695 or equivalent.
Install the sensor and tighten it to 30 ft. lbs. (41 Nm).
Attach the sensor electrical connector.
Connect the negative battery cable.