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Jeep Cherokee 1984-2001: How to Replace Oxygen Sensor

The O2 sensors help regulate the fuel economy in your Jeep Cherokee. When one stops working, not only does it lower the fuel economy, but it can sometimes lead to rough idling. This article will show you how to replace them.

By Jared Hammond - September 4, 2015

This article applies to the Jeep Cherokee XJ (1984-2001).

The O2 sensor, as its name suggests, measures the oxygen content flowing through your exhaust. If your Jeep was made between 1991 and 1995, then it has only one O2 sensor, but all Jeeps made after 1996 have two O2 sensors. One is the upstream sensor, which measures and regulates the air-fuel mixture in the engine, and the other is the downstream sensor, which measures how well your catalytic converter is working. The O2 sensors will typically start to fail between 100k to 150k miles, and the only real solution is to install a new one. You'll want to replace both of them because if one is out, the other is likely on its way out and there's no easy way to tell which one has failed.

Materials Needed

  • Replacement upstream and downstream O2 sensors
  • O2 sensor wrench or large adjustable wrench
  • Lubricating oil
  • Anti-seize grease

Step 1 – Remove the old O2 sensors

Make sure you disconnect the negative (black) terminal on your battery before you begin. Locate the upstream and downstream O2 sensors. They should be pretty easy to see. The upstream sensor is located on the bottom of the exhaust manifold near the engine. The downstream sensor is located on the exhaust pipe near the catalytic converter.

Simply remove the O2 sensor using your wrench. It might be difficult if it has become rusted into place, in which case you may want to spray some lubricating oil on it. Once the O2 sensor is out, unplug the electrical connector. Then repeat for the other sensor.

Figure 1. Upstream O2 sensor.

Step 2 – Install new O2 sensors

Before you install your new O2 sensors, be sure to apply some anti-seize grease to the threads so it'll be easier to remove in the future. Don't get any grease on the sensor or it won't work properly. Make sure you're installing the right sensor to the right position. Remember that the upstream sensor goes to the exhaust manifold, while the downstream sensor goes near the catalytic converter. To install the sensor, tighten it down with your wrench and then plug in the electrical connector. Repeat the same process for the other sensor.

Figure 2. Downstream O2 Sensor.

Pro Tip

There are typically two kinds of fitments for O2 sensors. OEM fitments just need to be plugged in, but universal fitments usually need the wires to be spliced together. Even though OEM fitments are more expensive, the convenience makes them worthwhile.

Featured Video: How to Change O2 Sensor

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