NorCal124

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.

NorCal124

1. First disconnect the sensor plugs located under the passenger side carpet.

NorCal124

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.

NorCal124

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.

NorCal124

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.

CDP

What can I say, you love me so that's why you do such nice things for me. Thanks for the write up, I'm sure everyone else will find this helpful besides me.

shadowgriffen

great write-up norcal

Kestas

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.

NorCal124

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.

Nick_M_51988

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.

jean_pierre84

what difference this sensor makes? the car perfomance changes??? excuse my ignorance please

kjb55

Jean - you have asked a very important and valid question. I'm at AAPEX this week but will be able to research the difference in ceramics used. From memory - I do not believe that the Ford and MB sensors use the same thimble body.

If cost is the issue - I strongly suggest using the Bosch Universal Sensor applicable to the MB model.

NorCal124

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.

CDP

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.

Kestas

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.

ashman

hehe I've seen you drive chris... I don't think you can cruise... hehehe LOL

I think your right foot is made of lead.

Alon

CDP

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.

NorCal124

No worries buddy, I'll let you know if I pick up any miles, but you seriously need to start doing some of your own work. It's both fun as hell and saves you a bundle.

CDP

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?

NorCal124

Yeah but those things take forever to get in the mail. I guess its worth the wait.

CDP

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?

flyaway718

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

yhliem

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?

Kestas

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.

floodkid

Thanks alot Nor
just changed my O2 sensor

ended up buying the right one ($140) but the step by step still helped things go alot smoother.

Thanks again