Replacing Oxygen Sensors
Russell Yee wrote about minivan oxygen sensor replacement
To change the O2 sensor [on 1995 3.0-liter Caravan for Russell, but likely in most other vehicles as well], the easiest way is to get way under your vehicle either on a lift or ramps that will let you get your head as far back as the catalytic converter or so. From there you will have a clear view of the sensor and plenty of room to reach it with even a short ratchet. You will not need any extension, u-joint, or any other special effort. You can easily reach the connector too.
Many parts stores (e.g., AutoZone here in Oakland) lend O2 sensor sockets for free (it has a slot to clear the wires). It seems to me that a crescent wrench could do the trick too.
It is possible to change the sensor from above but you have to be a contortionist even if you take out the air box. If you change from below but only go as far back as directly underneath the sensor you will have to work "blind" because you won't be able to even see it. Just wait til the exhaust is safely cool, slide way back, and it's a snap.
Edward R Hennessy wrote about replacing the sensor on an EEK:
Drive my usual 28 mile commute home. Let the car cool about 30-45 minutes. Take the o2 sensor socket, 3/8" to 1/2" inch drive adapter, 1/2" drive ratchet, 1/2" universal joint, and 19" 1/2" drive extension over to the car. Remove the airbox completely. Unplug connector. Install socket on sensor, attach ratchet handle, crank, and out it came (didn't need to spray or anything--this thing was in there for 72,000 miles, though). I didn't need the u-joint and extension, since there was plenty of room for the socket and handle with the airbox removed. Total elapsed time, 20-30 minutes at most.
If it was stuck in there, though, it would have taken me a lot longer, but the 1/2 inch drive really helps (and I was ready to swap the ratchet for a 1/2" drive 19" breaker bar if needed, then add the extension and u-joint if I had to, so it might not have been that bad).
Use the right tools and it goes a lot easier. But I was surprised at how easy the access was once I removed the airbox completely. I dreaded the job at first not because it might be seized, but that access was awful (until I re-thought it).
Not every vehicle is that easy! - an alternative guide by James Dement
I had 120K miles on my 3.3L Grand Caravan and had recently gotten a code 51 (lean condition). This code doesn't mean that your oxygen sensor is bad, but then again it could be so I elected to change my O2 sensor because it had never been changed. I think most of what I've written will apply to most any of the vehicles with the 3.3L V6 engine.
You would think that changing out the O2 sensor would be as simple as unscrewing the old unit and screwing in the new one. Wrong.
You might be able to see the sensor from looking behind the engine but unless you arms are as long as a monkey's and as tiny as a midget's then you can forget about getting to the sensor from above. You should however disconnect the wiring plug from above before going underneath to try and loosen the sensor.
Then, from underneath the van/car you can with difficulty get to the sensor. I'd let the engine cool as it is almost impossible to not touch the hot exhaust pipe. You might spray some penetrating oil on the area as the sensor generally is VERY hard to remove. You will need a 7/8" or 22 mm wrench or socket. I couldn't undo mine with a wrench so I had to stop and find a socket. You can buy a special socket for about $13, but I just made mine from an older deep socket. I cut a slot up one side about 3 inches so the socket could fit over the wires without cutting the wiring off. After much work and effort I got the sensor to break loose then unscrewing it was easy - - if you can call laying on your back easy.
I tried bench testing the old sensor with a meter and a propane torch but I couldn't tell anything.
I elected to buy the new sensor. This is a 4 wire unit and matched the original almost perfect. Pep boys sells a similar one from Borg Warner for about $47 that would probably be a good choice also. Others have posted problems with Bosch oxygen sensors so I didn't want to take a chance with them.
Someone (sorry forgot who) said to tie a string on the wiring connector before installation. I found that to be a wonderful idea after trying without luck in getting the new one started. The wiring is in the way and if you pull the wiring up with a string and attach it to the top side of the engine then you can twist the sensor without the wiring messing you up. If you don't understand this - you will after trying to install the new sensor. Just remember the string trick.
Finally got the new sensor started and tightened it up. Then wiped the exposed part of the sensor to remove any junk I'd gotten on it and went top side to attach the wiring connection.
Job now done. Sounds simple enough but at least the first time for me it took a long time. I'll have to wait now and see if I can tell any difference in mileage or if the code goes away.
I might also add that a mirror is almost required as you will not be able to see the hole or nut for the sensor from below. I hope this helps others.
Ted Mittelstaedt
I just did my O2 this weekend... on my 1995 Chrysler Town & Country with 3.8L engine.
The O2 sensor on this vehicle is really easy to get out if you have the right tools. You first need an O2 socket with a 1/2 drive. Get a really high quality one, the cheaper O2 sockets are shorter, and the O2 sensor is quite tall. In fact if you don't have an O2 socket, buy the O2 sensor first then have it with you when you buy the O2 socket. Next you need a 1/2 flex head stubby ratchet, (Harbor Freight sells a set of 3 of these which are perfect for this) and a length of pipe. The pipe slides over the ratchet handle.
The reason you want a flex head ratchet is because the angles are such that a regular ratchet will not fit in the space, nor will an assembly of u joints or suchlike. While Craftsman and SnapOn make really nice flex-head rachets, you won't be wanting to destroy them with a length of pipe.
The O2 sensor should come out with moderate pressure. If it doesen't one trick is to buy a can of Freez-It Freeze Spray from an electronics tools supplier (or other circuit freezing spray) and while the vehicle is up on jackstands, run the engine for 10 minutes to get the exhaust manifold good and hot, then shut it off and soak down the O2 sensor with the freeze spray pretty good, then try breaking free the O2 sensor. Wear heavy leather gloves and a leather jacket to guard against burns.
It also helps greatly to have the vehicle pretty high up on jackstands. Use good jackstands. The best I've come across are the Harbor Freight ones, they go on sale from time to time and have nice wide bases and and go quite high.
Unplug the sensor from the top before you start unscrewing it. Once you get the sensor tightened in, make sure to fasten in the top wiring to the bracket before you get out from under the van.
One other thing there are a number of sensors that my auto parts place claimed were matches to this. Some had plugs and others didn't. Before buying the new sensor, unplug the old one from the top and look carefully at the connector to see what it looks like.
Neon
We have a full section on this in the Neon repairs area; essentially, it's easy once the airbox is out.
Warning
From Mark McMackin, Chrylser Group Senior Specialist: “Don’t spray silicone or WD40 in the connector. Those two fluids will kill an O2 quicker than lighting. The sensor needs to breath oxygen (O2) and it does it through the wiring. Silicone will send a sensor’s output south so fast you won't know what hit you.”
Also see replacing Neon oxygen sensors.
