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Discussion Starter · #1 ·
I am trying to remove the passenger side front sensor on my 4wd 99 troop.
NO Way! I was under the truck trying everything and actually got my hand stuck trying to find any kind of access to get a wrench on the thing. I did hear someone say something about taking out the seat and pulling up the carpet and getting at it from above. Anyone done this????
ANY HELP appreciated!!
 

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I can only offer this:
When replacing all 4 of the O2 sensors on my 1997 Rodeo (and why, oh why, are there four of them!?!), if I had not had a 3-inch body lift, I would probably still be under there right now, several years later.

To say that the forward-most sensors are a 'tight fit' is a huge understatement!

Best of luck to you!

Cheers!
Smiley
 

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I recently did this on my '01 Trooper so assuming you have an automatic it should be the same.

The hard part for me was disconnecting the O2 sensor wiring connector from the harness.

I did this while servicing my transmission and I found that having the transmission cross member out gives better access. It allows you to reach up and forward from the rear (more clearance for your arm).

It's challenging to unplug the O2 sensor from the wiring harness but not too bad. You will probably scrape and bruise your arm and this is the only hard one to do but it took me about 15 or 20 minutes total having the cross member out. If you swear profusely while doing this task it does seem to help (helped me anyway).

Something to consider if you are still having trouble.
 

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Discussion Starter · #4 ·
Thanks for the replies.
I also was considering how i was gonna either reach in my right pocket with my left hand to get my phone or chew my right hand off as it was really stuck :oops:
The part I wanted to remove was the drive shaft for the front tranny- as I could spin it to help remove my hand - it was held on by a bunch of allens but I didn't know how involved it was to take off :?: Not so sure about the trans cross member - I can look when I go back under this weekend - although am now scared to cram my hand in any small holes!!
Anyone ever go from the top? that harness is WAY the heck up there!!
Thanks
 

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The tranny cross member is 8 bolts (four on each side). A very long flat blade screw driver will also help work that connector.

It isn't as bad as it looks but you definitely have to figure out something that works for you.

I had my arm stuck up there too but no *quite* as bad as you. The commend about chewing it off made me lol.

If you drop the cross member you can also lower the tranny a bit which helps even more.

If you do consider dropping the cross member get a trans filter and gaskets and kill two birds with one stone (do the trans service).
 

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Smiley said:
I can only offer this:
When replacing all 4 of the O2 sensors on my 1997 Rodeo (and why, oh why, are there four of them!?!), if I had not had a 3-inch body lift, I would probably still be under there right now, several years later.
OBD2 vehicles like your '97 Rodeo have a sensor before and after each catalytic converter. The sensor before the cat is used by the PCM to control the air/fuel mixture. The sensor after the cat is a reference cat that tells the PCM if your catalyst is functioning properly (by comparing the data from the sensor before the cat with the data from the sensor after the cat).

Generally speaking you don't need to replace the sensors after the cat unless you are getting a code saying the sensor is bad or the cat is malfunctioning (cheaper to replace the sensor before the cat).

At least on my '01 Trooper all four O2 sensor are the same part number which is nice. Often time the pre-cat sensors have a different part number than the post cat sensors.

Denso recommends replacing the sensors every 100K.
 

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Discussion Starter · #8 ·
I saw that tool but it looks easy to get to three of the four. My truck actually blew codes po137 bank 1 sensor 2 & po157 bank 2 sensor 2 which are both the rear ones. I had just passed the 90k mark so re-set the CEL and blew 0137 again on heavy highway acceleration. Thought I would go ahead with all four and start with the hardest which is bank 1 sensor 1 - didn't get under truck today but nay have another go tommorow -is changing all four a good idea or a waste of $ :?
 

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When you get codes from the rear ones it could be the sensors or it could be your cats are failing. Too bad I had four good but high mileage O2's that I threw out last week. I could have sent them to you for testing.

Denso recommends changing O2 sensors every 100K. The stock sensors are Denso and I would get the same if you change them. The best price I found was from Amazon.com when I bought mine.

If you want to change all four or even some it is your call but first you need to figure out if the sensors are bad or if your cats are bad.

I would suggest this... Pull the left front sensor and swap it with the left rear sensor and reset the codes. If your code moves to bank 2 sensor 1 then you have a bad sensor. If you get another Bank 2 Sensor 2 code then you have a bad cat. Once you figure that side out move the original Bank 2 sensor 1 over to Bank 2 Sensor 2 and do the same test.

You need to know if you have failing cats otherwise you are just throwing parts at it.

Make sure to put antisieze on the O2 sensor threads. The new Denso sensors come with it but add some to the threads for your swapping exercise and don't get any antisieze on the tip of the sensor.
 

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Discussion Starter · #10 ·
Those are great ideas - I had too many "honey do's" and Moms day to get anything done this weekend.
This morning I blew 6 codes :(
PO137 & PO137AD, PO157 & PO157AD
and the new one 1171 & 1171 AD - "fuel sys lean during acceleration" -
the reader also said the following " Severity unknown call 1-800-228-7667"
Anyone ever seen that? not even sure who the phone number goes to?
I also never mentioned that I SMELL GAS alot especially after I shut it down and mileage is way down around 11 does this help pinpoint anything??
 

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Sounds like you may have an IMG (Intake Manifold Gasket) leak. Common problem.

You might want to listen around the base of the intake for a leak (whooshing sound) or spray some carb cleaner along the base of the intake where it meets the head. If there is a leak you will immediately hear the difference when you kit the spot with some carb cleaner.

IMG would be my guess based on what you are saying here.
 

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I know this is an older thread, but I went through the process of changing out O2 sensor Bank 1 Sensor 2 today (my first time changing an O2 sensor!), and I thought I'd share some of what I learned for others like me who might go through the process in the future.

First off, I have a 1999 Isuzu Trooper with about 150,000 miles on it. My check engine light went on a few days ago, and after borrowing an OBD2 scanner I got back two codes. One code was for the O2 sensor, and the other was for the fuel running high (probably because the sensor was out). So I went to work fixing the problem by first reading all about it on the internet. Here's what I found. First of all, the best way to find a good diagram of what you're dealing with is by using google image. I searched something like "O2 sensor diagram Isuzu Trooper" and this is what I found: http://www.justanswer.com/car/3pbu2-cha ... front.html

The thread has awesome diagrams and an explanation of which sensor is which. For my trooper, Bank 1 is on the right hand side, and Bank 2 is on the left hand side. Sensor 1 is in front of the catalytic converter on both sides and sensor 2 is behind the catalytic converter on both sides. So I crawled underneath the passenger side and went to work on freeing the old sensor. There are two clips holding the pigtail of the sensor in place. There is a plastic piece on the bottom of the plastic connector that holds it firmly to a piece of metal just below the connector, and there is another plastic piece that holds the wires just behind the connector. I unclipped these with a screwdriver, although it took a little creativity to get the screwdriver in the right place. There just isn't a lot of working space down there! I also bought a special O2 sensor socket because it was suggested in one of the threads, only to find out that once I got it in place, there was no way to get my ratchet handle attached to it. Though the special socket may be helpful for the other three sensors, it is not useful for bank 1 sensor 2. I scrapped the idea and quickly found that a normal open ended wrench was well suited for the job. I had to bang on the end of my wrench a few times with a hammer, but it wasn't long after that that the old sensor was out and the new one was in.

After disconnecting the battery and reconnecting it, the check engine light is off again and the Trooper is running great. The whole process took me a little over an hour, but I would imagine that it would be a lot faster for someone with more experience.
 

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I use a open end wrench to loosen and tap with hammer. Worked on bank2sensor1 on my 04 rodeo. Going to replace bank1sensor1 tomorrow. Take your time with connection,so you don't cut your hands and use screwdriver to unlock. Good luck,Tony
 

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2002 Isuzu Trooper - I have never replaced a 02 sensor in my life but i like to figure things out my self, i looked at some forms on here and google and seen that it appears to be a PITA to change the 02 sensors on the trooper.. I am 22 years old and managed to do this my self. Check Engine light has been on probably 5 months now lol, i knew i was getting heat circuit sensor trouble codes P0134,P0135 & P0154

Bank 1 Sensor 1 - Driver Side, Before CAT
Bank 1 Sensor 2 - Driver Side , After CAT
Bank 2 Sensor 1 - Pass Side - Before Cat
Bank 2 Sensor 2 - Pass Side - After Cat

I am glad i attempted to do this my self and not put it in a shop. I used a open combination 7/8 wrench. I was able to disconnect the connectors within 2-3 min. , Yeah they are a little hard to get to but if you get it at the right angle and pull the clip up with one hand & and pull on the wire away with other, it will come right off..... After i had the wire disconnected i just snipped all the wires off so i could get a closed end wrench over the 02 sensor (wanted to get a good bite on the nut) and remove the sensor. Bank 1 sensor 1 was no problem at all, a little tight to get off but what do you expect with it being 12 years old .Bank 2 sensor 1 was more difficult due to little room to work with but with some lube and a piece of pipe over my wrench i was able to remove it with no problem. Be careful because the heat shield gets in the way and if you do not pull it down with your hand you will not get a good bite on the sensor and it will strip. Also A open end 02 socket will not work, there is no room for a socket or room to even turn it if it would fit.
You have to have patience because there is not much room to wrench so it takes 3 to 4 times to get a full turn on the nut. Long story short i had both Bank 1 & 2 sensor 1's replaced within 2 hours. I used Bosch 15703 Oxygen Sensor @ $24 on amazon.Works on both upstream / downstream locations. Remember WD40 is your best friend, and a torch will help expand if needed.

-Tyler
 

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twilson said:
2002 Isuzu Trooper -
Bank 1 Sensor 1 - Driver Side, Before CAT
Bank 1 Sensor 2 - Driver Side , After CAT
Bank 2 Sensor 1 - Pass Side - Before Cat
Bank 2 Sensor 2 - Pass Side - After Cat
-Tyler
You have banks reversed, bank 2 is on the left side (driver) of the vehicle.
 

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Crap. I need 2 more not one. Theyre a pain to get out but I changed 2 in the O'Reillys parking lot. Took an hour to het them out. Should be easier for the other 2 with my tools at home. Only had channel locks and a crescent wrench for the first 2. The next 2 will go much smoother. Realized a lift woulnd hurt either. Hard to move under mine and I'm a skinny guy.
 
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