Oxygen Sensor Install
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Joined: Apr 2005
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From: Northern Cali
W124
Oxygen Sensor Install
I recently did the O2 sensor install on my 124. I actually did the install suggested by jrmd01 where you take the O2 sensor from another vehicle and splice it into the connectors of the OEM sensor. The other reason I did this is because Chris isn't smart enough to do this himself and he needs someone to hold his hand and show his sorry @$$ this simple task. j/p
What you will need:
- Wire splicer
- Soldering rod/gun
- Sodder
- Heat shrink or electrical tape
- Adjustable wrench
- Small flathead screwdriver
- Oxygen sensor (Bosch p/n - 13953)
Here are some comparison pics of each sensor before I go into the step by step instruction.
What you will need:
- Wire splicer
- Soldering rod/gun
- Sodder
- Heat shrink or electrical tape
- Adjustable wrench
- Small flathead screwdriver
- Oxygen sensor (Bosch p/n - 13953)
Here are some comparison pics of each sensor before I go into the step by step instruction.
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From: Northern Cali
W124
2. Next, lift the car from the left side using a floor jack and jack stands (it was easier for me to use two jack stands). Once lifted locate the O2 sensor positioned about one foot back from the transmission oil pan. Remove the heat shroud that clips over the sensor and then undo the O2 sensor using an adjustable wrench. I found it easier to remove the sensor by pulling through the rubber grommet and connector from inside the compartment.
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From: Northern Cali
W124
3. With the sensor removed you can begin to splice in the new sensor. When splicing the connector into the new sensor be sure to note which wires are which. I differentiated the wires by their positions to the left or right of the black wire using tape to indicate their location (do this on both sensors before cutting). Once that is complete cut and splice each wire one at a time. Slide the heat shrink over the spliced wire prior to soldering them together. Do this on the two remaining wires. As a precautionary measure you can further wrap the wire in electrical tape.
* PLS. NOTE: The pictured splice near the connectors is a second splice I made because the wire was too long and I wished to shorten it.
* PLS. NOTE: The pictured splice near the connectors is a second splice I made because the wire was too long and I wished to shorten it.
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From: Northern Cali
W124
4. Lastly, install by reversing the removal process and attach the connectors. It is also easier to re-insert the grommet using a small flathead screwdriver. After that you're done.
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From: Motor City
95 E320 Cabriolet, 108K
Good write up. Let me add a few comments.
Sometimes it's better to stagger the splices. That way you don't get this pregnant mass of wire bundle in one spot when threading it through the hole.
I have yet to buy a socket for O2 sensor removal. I've always gotten by threading the pig tail wiring through a box-end wrench, which gives more purchase than an open-end wrench.
Sometimes it's better to stagger the splices. That way you don't get this pregnant mass of wire bundle in one spot when threading it through the hole.
I have yet to buy a socket for O2 sensor removal. I've always gotten by threading the pig tail wiring through a box-end wrench, which gives more purchase than an open-end wrench.
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Thread Starter
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From: Northern Cali
W124
You won't need a socket to remove the O2 sensor on W124s because its not situated in an ackward position like on an exhaust manifold. You can use a simple adjustable wrench for this one.
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From: Modesto, CA
1992 400E (86 300E, 98 S420) - Retired
thanks alot. i just went to the stealer and got a quote for a o2 sensor. it scared me.
i think i'll head to kragen this weekend and pick up a sensor. my gas milage is like 12 mpg. but i drive it hard.
i think i'll head to kragen this weekend and pick up a sensor. my gas milage is like 12 mpg. but i drive it hard.
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From: Chicago
2025 AMG E 53; 2018 GLC300 4Matic; 2003 360 Modena
Originally Posted by jean_pierre84
what difference this sensor makes? the car perfomance changes??? excuse my ignorance please 
If cost is the issue - I strongly suggest using the Bosch Universal Sensor applicable to the MB model.
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From: Northern Cali
W124
12mpg, OMG! I don't know how you can live with that.
kjb55: I believe the univ. specifically for the MB is only 20 bucks cheaper than the 160 an OEM one costs, I know because I sell auto parts.
kjb55: I believe the univ. specifically for the MB is only 20 bucks cheaper than the 160 an OEM one costs, I know because I sell auto parts.
Last edited by NorCal124; Nov 3, 2005 at 02:13 AM.
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From: Orange County, CA
W124's
I'll probably tackle this O2 sensor replacement this weekend since I'm tired of paying 45 bucks a week on gas even when I don't drive that hard most of the time. Gotta cruise to show off the bling bling. 
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From: Motor City
95 E320 Cabriolet, 108K
I believe many of the different part numbers for (Bosch) O2 sensors are simply because of the different pigtail connectors. We know there should be differences among the 1-, 2-, 3-, and 4-wire designs. I also believe many of these different sensors share the same sensor (body and sensing element).
What I'd like to know, is there a source, like a Bosch technical catalog, that can tell us which O2 sensors have the same sensor design? This way we can choose the cheapest sensor to splice into the existing connector. In addition, we could then figure out which connector to buy, since the '90 Mustang 302 connector is not sold anymore.
What I'd like to know, is there a source, like a Bosch technical catalog, that can tell us which O2 sensors have the same sensor design? This way we can choose the cheapest sensor to splice into the existing connector. In addition, we could then figure out which connector to buy, since the '90 Mustang 302 connector is not sold anymore.
hehehe LOL
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W124's
lol. Please don't count that time I was hauling *** off the off ramp to meet up with you. 
I've taken it easy lately on the car, not that much of driving it hard anymore. Especially since I have no more brakes in the front. lol
Also, I'm going to make a visit to Kragen later to see how much they can give me that Bosch Sensor for. Thanks for posting the P/N chris.
I've taken it easy lately on the car, not that much of driving it hard anymore. Especially since I have no more brakes in the front. lol
Also, I'm going to make a visit to Kragen later to see how much they can give me that Bosch Sensor for. Thanks for posting the P/N chris.
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From: Orange County, CA
W124's
lol. You swear like I'm going to pay someone else to install this for me.
By the way, 48 bucks at the local Kragen, but I'm buying it this weekend. Supposely you get a 10 dollar gas card with purchase. haha Can you confirm chris?
By the way, 48 bucks at the local Kragen, but I'm buying it this weekend. Supposely you get a 10 dollar gas card with purchase. haha Can you confirm chris?
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W124's
So I replaced the O2 Sensor on friday, doesn't seem like my gas mileage has improved.
I'm wondering, could there be any other contributing factors that could lead to bad gas mileage?
I'm wondering, could there be any other contributing factors that could lead to bad gas mileage?
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E320 Year 2000 4Matic Oxygen Sensor o2
I need to replace the 2 rear O2 Sensors. Does anyone know if this is the right part?
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT
Thanks
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT
Thanks
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Just a thought, but rather than replacing the connectors on the O2 sensor, wouldn';t make more sense to make an adapter so that you don't have to go through the whole process again the next time you might need to replace your o2 sensor?
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From: Motor City
95 E320 Cabriolet, 108K
That's what I was suggesting in my post above (Post #15). Some time ago, someone figured out which cheaper replacement is the same as the Mercedes O2 sensor. It was in the following dead link:
http://hsb.baylor.edu/html/easley/mercedes/welcome.html
That particular sensor happened to be one from a 90 Mustang 302, and the proper adaptor was identified by part number, allowing anyone to go to the Ford dealer and buy the adaptor for $9.06. But alas, the dealer doesn't supply this adaptor anymore. It's not on their books.
If I had access to a good Bosch O2 sensor catalog, I could perhaps figure out which applications use the same O2 sensor and find which manufacturer sells a connector to match. I tried getting information from the internet, but there's just not enough detail.
The Mustang sensor fit a lot of older models, but it didn't fit my model.
http://hsb.baylor.edu/html/easley/mercedes/welcome.html
That particular sensor happened to be one from a 90 Mustang 302, and the proper adaptor was identified by part number, allowing anyone to go to the Ford dealer and buy the adaptor for $9.06. But alas, the dealer doesn't supply this adaptor anymore. It's not on their books.
If I had access to a good Bosch O2 sensor catalog, I could perhaps figure out which applications use the same O2 sensor and find which manufacturer sells a connector to match. I tried getting information from the internet, but there's just not enough detail.
The Mustang sensor fit a lot of older models, but it didn't fit my model.
