How to Replace a O2 Sensor In a Chevy Astro

The oxygen sensor on your Chevy Astro monitors the oxygen to burned fuel ratio and communicates that mix to the computer. When it picks up an unacceptable variance in that mix, it triggers the malfunction indicator light (MIL) and illuminates the "Service Engine Soon" light. There are two oxygen sensors on your Astro Van, and you will need to determine which one (or if it's both) needs to be replaced. An auto parts store where you'd buy the replacement sensors could plug in a code reader and determine this information for you.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Car ramps
• Wheel chock
• Oxygen sensor socket
• Anti-seize lubricant
• Flathead screwdriver
• Direct fit oxygen sensor(s)
• 3/8-inch drive ratchet
• Safety glasses
• Creeper (optional)
• Portable hand torch (optional)

How to Replace a O2 Sensor in a Chevy Astro

1. Drive the Astro Van up onto the car ramps on a level surface. Apply the parking brake and release the hood latch. Place a wheel chock behind one of the rear tires and open the hood to allow a little light down through the engine compartment.

2. Put on the safety glasses and crawl under the Astro with all the tools and a creeper if you have one.

3. Locate the oxygen sensor(s) that need to be replaced. The front sensor or "sensor one" is located up on the driver's side of the front exhaust Y-pipe. The rear sensor or "sensor two" is located near the catalytic converter on the passenger side of the undercarriage.

4. Trace the wire that is attached to the sensor until you locate the plug, about 7 to 8 inches away. Disconnect the plug by pressing in the clip lock, using a flathead screwdriver and pulling the plug assembly apart. Place the wire of the sensor through the slot of the oxygen sensor socket and snap the ratchet into place on the back of the socket. Try to loosen the sensor. If it does not move under force, you may have to heat up the exhaust pipe area surrounding the sensor. Do not heat the sensor, too. You want to expand the metal of the pipe and not the metal of the sensor as well. Remove the sensor.

5. Allow the exhaust pipe ample time to cool down before continuing if you had to use the torch. If not, apply a light coat of anti-seize lubricant to the threads of the new oxygen sensor. Some quality after-market replacement sensors may come equipped with some lubricant already on them. Be careful not to get the lubricant on the sensor itself.

6. Screw the sensor into the threads of the porthole and tighten with the socket and wrench. Do not overtighten and risk stripping the threads of the new sensor.

7. Reconnect the plugs of the sensor to the wire harness.

8. Repeat this step for the other sensor if necessary.

9. Remove tools and old sensors from under the Astro. Remove the wheel chock close the hood, release the parking brake and back off of the car ramps.

Tips & Warnings

• Ask the auto parts store where you bought the oxygen sensors if they'd be willing to reset the computer again after you replace the sensor. You don't have to, but it would ensure that the sensors were okay and that it's not another problem in the Astro making the sensors fail.

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