C-Class (W203) 2001-2007, C160, C180, C200, C220, C230, C240, C270, C280, C300, C320, C230K, C350, Coupe

DIY: M271 O2 sensors

Old Jul 18, 2007 | 05:49 PM
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DIY: M271 O2 sensors

I want to change both myself and post a write-up yet need some help.

From the engine bay I cannot see where the sensor plug is. The wire runs from the sensor, over the transmission, and to the drivers side yet I cannot see where it ends and where the plug is.

Has anyone changed them?
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Old Jul 19, 2007 | 07:41 AM
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Come on, someone with the DVD manual help me out so I don't have to crawl under the car to find the plug.

Please!

Maybe I should just order the manual.
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Old Jul 19, 2007 | 11:53 AM
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Bump until someone helps me out.
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Old Jul 19, 2007 | 11:59 AM
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Yo - I've never actually done a replacement of an O2 sensor yet.. only for header installs (to remove them temporarily - but not replacement). You're talking about replacing the wiring altogether for an OEM new one right?
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Old Jul 19, 2007 | 01:20 PM
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Originally Posted by mig888
Yo - I've never actually done a replacement of an O2 sensor yet.. only for header installs (to remove them temporarily - but not replacement). You're talking about replacing the wiring altogether for an OEM new one right?
Yeppers!

Need to find where the wiring goes to unplug it. I have removed the sensors from the header many times, just never removed the sensor from the vehicle.
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Old Jul 20, 2007 | 01:19 PM
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bump.

come on, someone with the manual please help me out!
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Old Jul 20, 2007 | 01:41 PM
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Can't you just ask a service tech at your local dealer? Mine has always been pretty helpful when I come with questions, and has even "given" me a couple of misc. parts at times, with enough Best Buy giftcard tithes.
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Old Jul 20, 2007 | 02:06 PM
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I'm looking again, had the same question. After I got this OBD II scanner I found I don't need to change them now. Give me a few minutes to look.
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Old Jul 20, 2007 | 02:16 PM
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Originally Posted by tommy
Can't you just ask a service tech at your local dealer? Mine has always been pretty helpful when I come with questions, and has even "given" me a couple of misc. parts at times, with enough Best Buy giftcard tithes.
I have before, yet they are booked 3 weeks in advance right now, so they are too busy to spend a few mins and help me look something up.

I really need to order the DVD manual if I am going to keep this car.

Thanks Russell_Stevens, that would help me out!
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Old Jul 20, 2007 | 10:19 PM
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I can't find the plug for the 271, only the 112. It just says to unplug it.
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Old Jul 30, 2007 | 10:04 AM
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No-one has changed the O2 sensors on their M271?
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Old Sep 9, 2008 | 04:32 AM
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the plug is clipped onto the side of the transmission, access from the bottom.
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Old Sep 9, 2008 | 01:50 PM
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Take off belly panels under the engine and then you will see where the O2 sensors wires lead to. It is under the bottom left of the engine. Just follow the sensor wires! It takes a whole 15-20 minutes to do including jacking the car up.
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Old Sep 9, 2008 | 02:15 PM
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Ive been under my friend's c230k and im pretty sure if you just take off the panel that covers the oil pan, you should be able to see the o2 sensors...

I have no idea how you'd unplug them though... do keep us updated: would be nice to see how its done
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