How to Replace an 02 Sensor in a 95 Astro Van

There are two oxygen or O2 sensors in the exhaust system on the 1995 Chevy Astro van. The process of changing the O2 sensors is the same whether it is the upstream or downstream sensors that you need to change, except that the location is different. These O2 sensors are critical to the proper operation of the fuel system and performance of the engine in your van. If you have a bad sensor, change it right away to correct drivability issues, hard stats and poor fuel mileage.

Instructions

1

Raise the front of your Chevy Astro with a jack and support it under the frame rails with a set of jack stands. Remove the jack once the van is securely on the stands.

2

Locate the O2 sensors from under the van. The upstream sensor threads into the exhaust pipe coming down from the engine manifold. It is on the inside edge of the pipe, closest to the engine block. The downstream O2 sensor is in the exhaust system just forward of the catalytic converter.

3

Determine which sensor you need to change, and position yourself below it. Locate the wiring harness coming out of the back of the top of the sensor and follow it up to the connector where the sensors harness and the vans wiring harness join. Disconnect the two halves of the connector by releasing the locking tab and pulling them apart.

4

Remove the O2 sensor from the exhaust pipe using an O2 sensor socket and ratchet to turn the sensor counterclockwise until it is free from the threads. Discard the old sensor and install the new one into the threaded hole on the exhaust pipe using your hands to get it starter. This will help prevent cross threading.

5

Tighten the O2 sensor with your O2 sensor socket and ratchet. Run the wiring harness connector from the new sensor up to the connector on the vans wiring harness. Push the two halves of the connectors together until the locking tab engages. If you are replacing both sensors, move to the other sensor and repeat the process.

6

Raise the front of your Astro off the jack stands with a jack. Remove the stands from under the van then lower the jack, setting the van back on the ground. Test run the engine to verify the sensors are functioning properly.