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  #1  
Old 11-12-2003, 07:00 PM
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Replacing Oxygen Sensor on 95 E420, HELP!

Has anyone done this on this car? how easy/difficult is it? Any special tools? I am average on DIY stuff. Any detailed instructions (wow with pictures maybe!!) will be great! Thanks folks.
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  #2  
Old 11-12-2003, 11:16 PM
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It fairly hard to get to - located in the Y where the two exhaust pipes come together in about the center of the car. You really need a special tool - an open socket of that size. I had never seen one before - it's like a 300 degrees socket with an opening on the side of the socket to slip on from the side. I was fortunately able to borrow one from a mechanic and the job then became quite doable - put clearly the tool was the key. My recollection is that I had to raise just one wheel, the left front, on a jackstand.
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Old 11-13-2003, 12:07 AM
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Other than having the special tool...

was it easy to get access to once the left front is raised? Also how about the connector side, was that also easy to access to disconnect/reconnect? Thanks for your feedback.

Anyone else has any other tricks up their sleeves to help simplify this task? Also any torque settings i need to be aware of? Also would I need anti-seize paste?

P.S. I was able to find the tool you are talking about on eBay for $10.00 + $5 s/h.
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  #4  
Old 11-13-2003, 12:59 PM
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If yuur replacement O2 . . . .

sensor is like mine (and I think it will be), you'll find that it has a very long connecting cable.

If I remember correcrtly, MB doesn't make that 'version' any lanoger but a 'universal' one that fits a number of cars. You will have to fold the cable back onto itself and use cable ties (perferred) to get it to the right length.

The difficulty with this longer folded-back cable is that it wants to droop abit and it could rest on the exhaust pipe, a definite no-no. Other than that it will really improve your car's performance and gas milage.

About 8 months ago, I replaced my MAF and O2 sensor. Since then the gas milage has been around 15.5mpg city and close to 20mpg freeway.

Also the fuel computer's S/A has gone to 0.9091 from 0.8389. I have my DTC#19 eprom in my car. But this is a very expensive solution: MAF price was $290, O2 was $78, wholesale prices.
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  #5  
Old 11-13-2003, 03:13 PM
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See picture.. How long is your O2 cable?

Jim,
Your car and mine use the same O2 see its photo below. I haven't received the part yet, but it look like the cable is about 12 " or so long... is this too long for the application where you need to fold it?
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Replacing Oxygen Sensor on 95 E420, HELP!-o2.jpg  
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  #6  
Old 11-13-2003, 04:06 PM
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Due to the location of the O2 sensor, you will need a box end socket (see pic). If I remember correctly, the size of the box end socket is 24mm.


Install in rerverse order: Coat thread of oxygen sensor with hot lubricating past and tighten to 55Nm on the v8 119m engine.

Hope this Helps...
Russell

I purchased my box end socket from Harber Freight
Attached Thumbnails
Replacing Oxygen Sensor on 95 E420, HELP!-box-wrench.jpg  

Last edited by rsmcmahon; 11-13-2003 at 04:18 PM.
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  #7  
Old 11-13-2003, 06:02 PM
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Thanks Russell

photo of tool and torque helps a lot.
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Old 11-13-2003, 06:30 PM
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I wouldn't say access was easy with one corner up but it was doable. I have no recollection of any problem disconecting or connecting. It was all underneath as I recall. I also don't remember any cable length problem - the part seemed specific to my car. It was a Bosch, maybe 18 months ago. I don't remember the size of the socket but I have since done a 300E O2 sensor that was 22 mm - I know because I had to buy an open end wrench and I still have it. 300E had a lot more room. In any case when you get the part you'll be able to figure out the size.
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Old 11-13-2003, 06:37 PM
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Joesph,

I'll check the size of the box end socket tonight when I get home. 22mm may be the correct size as suggested by deanyel. I also just used the tire jack to lift the car on the drivers side front wheel for more working area while gaining access to the O2 Sensor. BE SURE AND SECURE THE REAR WHEELS WITH SAFE blocks and use a jack stand or something safe to secure the car while it's lifted.

Russell
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  #10  
Old 11-13-2003, 07:09 PM
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I thought that we used the same . . .

O2 sensor but when I got the replacement, the 'blue' cable was at least twice as long as the original one, thus my comments.

As I remember, I checked with the MB dealer and he said that this is MBs 'universal' replacement sensor that is now being manufactured.

Anyway, no big deal as long as you take the time to make sure it doesn't touch the exhaust.

BTW, I did mine on a hoist; don't know if you can do it with one wheel up. At best, you'll get a workout!
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  #11  
Old 11-16-2003, 11:06 PM
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Done it !!! Jim was right!

Was able to left up the car from the driver's front side and rested a ramp underneath the front tire for safety. Crawled under their and had to use the special tool pictured above. It took longer to get used to the tool than it did to actually get the O2 out. I sprayed some penetrate lube and had to use some force to get this sucker outa there. There is no way one could use a regular wrench as some state in other posts !!! there is very small clearance to work with and the sensor is at awkward angle and fits into a deep socket almost like a spark plug so a regular wrench is not possible. I also used a 3" extension that plugged into the socket and then used a small wrench to fish the job. I was able to use my torque wrench to install it back with 50Nm (37 ft-lb) torque (calculate the wrench extension into that to make sure you get the correct torque. The job took me 15-20 minutes and I am an average or below DIYer.

JimF, you were correct, my sensor came with longer wire than the original. I followed your advice and folded the cable into itself and used 3 cable ties to secure it away from the exhaust. Glad you made the observation. Car already feels great!

oh, I was able to buy a new sensor from eBay for $77 including s/h. The sensor is brand new OEM (Bosch) and already comes with high temp lubricant on the thread and covered with plastic to protect it (see color photo above).
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  #12  
Old 11-17-2003, 02:23 AM
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Glad you were able . . .

to get it removed and replaced with a new one! Good deal!

Be interested if you periodically check the S/A of the fuel computer (LH-SFI). I would appreciate you sending (posting) the results. I think you will see it go up.
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  #13  
Old 11-17-2003, 01:27 PM
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Re: Glad you were able . . .

Quote:
Originally posted by JimF
Be interested if you periodically check the S/A of the fuel computer (LH-SFI). I would appreciate you sending (posting) the results. I think you will see it go up.
Jim, How do I do that? not sure if i need special tools for this. I would be glad to do so if within my capabilities.
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  #14  
Old 11-17-2003, 01:35 PM
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'94 S500: only 793 sold!
 
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You need a . . .

scanner that can 'do' live data such as the AST Retreiver. There are others that can peform that function.

Maybe you can get a indy tech to read those periodically?
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