2000 Cavalier o2 sensor replacement


Old 02-05-10, 07:37 AM
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2000 Cavalier o2 sensor replacement

In the process of trying to replace the downstream oxygen sensor on my son's 2000 Cavalier.

Of course the sensor is probably the original (bought the car used with 100K on it and now has 130K) and it looks like the threads of the sensor are welded into the exhaust pipe as there was so much rust built up.

I've cleaned the rust off the area where the sensor goes into the exhaust pipe and saturated with PB Blaster penetrant, but so far no luck on breaking it loose. Unfortunately, this is all being done by laying on the garage floor which doesn't really give me a lot of leverage to try to turn a wrench to get it loose. can't really get a oxygen sensor socket on the sensor due to the limited space

Even tried the suggestion of running the car for 15 minutes to heat up the pipe, but probably expanded the threads on the sensor at the same time the exhaust pipe was heating up, so this is just wasting fuel.

Any other suggestions on getting this broken loose?

Anybody have any idea where the connector end of the downstream sensor actually plugs in at? I've followed the wire along the floor pan under the car to the back of the engine compartment, but it seems to disappear in a jumble of wires.

Unfortunately, 6-8" of clearance under the car isn't helping with either the removal of the sensor or tracking the wiring.

Next process will be to put the car on some ramps, but I,m not sure this will give me enough space to get leverage on this sensor.

My Kingdom for a vehicle lift!!!
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Old 02-05-10, 11:14 AM
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I believe, If it was my little beast, I would first get a set of ramps - 20 bucks = dirt cheap. Then make sure you have a combination wrench size that would fit it and another combination wrench to add for leverage.

Then drive it for about the ten or fifteen minutes, not just idling, but at highway speeds to heat it up well. Then take it straight onto the ramps, cut the wire to the sensor and see if it'll break loose with just the boxed wrench on the sensor.

If you need more leverage use the boxed end of the second wrench on the open end of the one on the sensor for leverage. You can figure out how to fit the second one to the first pretty easy. That will give you about 20 inches of handle and that should do it.

Use "anti seize" when you reinstall. You'll just need the open of the combination to reinstall.
Old 02-05-10, 01:16 PM
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All my tricks...

Leverage helps - long handle on wrench.

Then heat on exhaust - heat makes things expand.

Cold on sensor (ice cubes) - cold makes things contract.

Also two people doing this, one placing lots of pressure on the wrench, the other hammering on the joint.

But even with all the above, the last oxygen sensor I removed did not want to come out! I cranked with all my might! (Finally got it with the hammering.)
Old 02-05-10, 05:41 PM
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Take it to a garage and for $20 they'll replace it. I gave up and think it was the best $20 I ever spent. The guy had to put a 3/4" breaker bar with some pipe on it to get it out.
Old 02-05-10, 06:53 PM
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been there on a 83 celebrity

A few thoughts.
-ramps wouldn't hurt and could be used on future projects like oil changes. It would allow you to crawl under there and chase the other end of that pigtail.
-Suprised about the PB Blaster. Try some 3 in one oil on where the sensor screws in. Let it sit over night (at least half a day.) It takes time for it to penetrate. Then try removing it.
-There's also a special socket made to remove O2 sensors. Autozone may have it in their "loan a tool" deal.

The autozone website has vehicle specific repair guides. No connection to the store; just a satisfied customer.

From the above site the procedure for this for your reference:

1. Disconnect the negative battery cable.
2. Unplug the electrical connector and any attaching hardware.
3. Remove the sensor.

To install:

4. Coat the threads of the sensor with a GM anti-seize compound, part number 5613695, or its equivalent, before installation. New sensors are precoated with this compound.

The GM anti-seize compound is NOT a conventional anti-seize paste. The use of a regular paste may electrically insulate the sensor, rendering it useless. The threads MUST be coated with the proper electrically conductive anti-seize compound.

5. Install the sensor and tighten to 30 ft. lbs. (40 Nm). Use care in making sure the silicone boot is in the correct position to avoid melting it during operation.

6. Attach the electrical connector.

7. Connect the negative battery cable.

Once you do get the doggum sensor out, take a look at it.

1) If the sensor tip has a black/sooty deposit, this may indicate a rich fuel mixture.

2) If the sensor tip has a white gritty deposit, this may indicate an internal anti-freeze leak.

3) If the sensor tip has a brown deposit, this could indicate oil consumption.

Take comfort that at least you are working indoors.

mobtown man

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