Monday, 5 October 2015

Replace An O2 Sensor Inside A 1998 Chevrolet Blazer

O2 sensors are compelled for monitoring exhaust.

The 1998 Chevy Blazer has three O2 (Oxygen) sensors. Two are located up on the front Y-pipe bolted to the V-6 engine's manifold. These two sensors detect the fuel-to-air alloy in the exhaust and give back that data to the powertrain charge module (PCM). From there, the PCM makes adjustments to accomplish the lowest emissions likely while even running properly. The endure Oxygen sensor is located after the catalytic converter. This sensor's job is to monitor the efficiency of the catalytic converter.


1. Apply the parking brake to lock the rear wheels.

2. Open the hood to the 1998 Chevy Blazer to allow some light down into the engine compartment. This will be helpful when under the vehicle to replace the front oxygen sensor(s). If you are replacing the rear sensor, opening the hood is not necessary.

3. Lift one front side of the Blazer up high enough to rest it on a jack stand and then lift the other side and rest that side on a jack stand.

4. Put on the safety glasses and crawl underneath the Blazer to locate the oxygen sensor(s) being replaced.7. Thread the O2 sensor wire through the closed end of the 22 mm wrench and then place the closed end of the wrench onto the sensor's hex-head. Turn the wrench to the left (counterclockwise) to remove it from the port.

Use the small screwdriver to press inward and release the lock while pulling the O2 sensor plug and wire away from the wire harness plug.

6. Spray penetrating oil around the threaded connection of the O2 sensor where it screws into the O2 sensor port of the exhaust piping. Allow the oil a few minutes to soak in.

One is located on the left-side Y-pipe up near the manifold connection, the other is on the right-side Y-pipe near the manifold and the rear sensor is located in the catalytic converter pipe just behind the shell of the converter.5. Unlock the wire harness plug from the O2 sensor plug. Remove the sensor.

8. Inspect the threads of the replacement sensor. Most will come with a light coating of special anti-seize compound already on the threads. Some O2 sensor manufacturers will provide a small tube inside the box. If applying the compound, be sure to avoid getting the compound on the thimble-tip of the sensor. Only place a small amount on the threads of the sensor.

9. Thread the sensor into the port by hand to avoid crossing the threads of the sensor. Tighten the sensor with the wrench after threading the wire through the closed end again. Only tighten the sensor snugly. Over-tightening the sensor risks stripping the threads of the sensor and/or possibly damaging the threads to the sensor port.

10. Connect the replacement sensor wire plug to the wire harness plug before crawling out from under the Blazer with the tools and old sensor(s) and lowering the vehicle.