Hi!

I need to replace the oxygen sensor on my 94 S500 so I bought a new one. THe new sensor has a loooong connecting cable whereas the old one only has about 6 inch long cable with a round connector at the end. Is there only one oxygen (I've read someplace about "upstream/downstream" stuff) sensor? If there is only one, what could be the problem with the cable?

Thanks in advance!

hi there...

just wondering what triggered you to replace the sensor and how much does it cost. What kind of effort are we dealing with??

Is this replacement related to teh age of your car, yours being 94, or miliage?

Thanks. Sorry I can't help but would love to know.

Thanks

The engine developed usual M119 problems - wiring harness, AFM (mechanical damage - a mechanic dropped something IN it, broke the protective mesh), spark plugs... Basically a part of an expensive tune up.

I am not sure about your particular car but, there are pre-cat & post-cat O2 sensors.

The pre-cat goes before the catalytic converter, whereas the post-cat goes into, or directly behind the converter.

That's about all I can give you, sorry.

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2007 C 230 Sport.

Thanks. The sensor that I was able to find is pre-cat, it is sitting right before the converter.

O2 sensor in your car; it's located just ahead of the 'Y' in the exhaust system.

Yes, it's true! the newer sensors have a (very!) long pigtail and that's what Bosch now makes which works for 15 (I think) Mercedes models.

What you need to do: use two (2) cable ties and coil it up so it's apx the same length of the original. That shortens it so it won't rub on the drive shaft.

I replaced mine recently (104K miles) and the car has more more 'pep'. My gas mileage dropped a bit and it appears that the new O2 sensor restored it, around 15mpg city, 21 highway.

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Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

Jim,

THanks alot for your advise. The second question remains - the old sensor is 4-wire, with round screw-on connector. The new one I got has 3 wires and a simple plug in connector so it won't fit. Should I do some wire splicing/taping here? If so, which wires go where?

Thanks in advance!

Sounds like you got the wrong part. From what I came up with there are two sensors that may fit your car based upon chassis number.
000 540 26 17 -up to A 080956
000 540 47 17 -from A080957
I hope this helps., Robert.

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Mercedes Benz Master Tech - Retired

000 540 45 17 with the 8" pigtail. The new pn stamped on the Bosch box was the same, 000 540 45 17 but it has the 2' pigtail. If I remember correctly, the marking on the body was the same.

I think the '47' number is incorrect and may be the non-heated version??? You need the round four (4) pin connector for your W140.

Here's a pic of the old one:

__________________
Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page