O2 Sensors DIY on my W212/E300/M276/2014
Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Leave the others sensors alone unless faulty.
Thread Starter
Newbie
Joined: Mar 2023
Posts: 12
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From: Seoul
E300 M276
Out Of Control!!
Joined: Apr 2019
Posts: 11,927
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
good pick!
The engine only runs as well as these sensors say it does. It's important to replace in pairs to keep engine banks balanced.
Enjoy the results as the ECU refreshes its fuel map. You'll get improved throttle response like new again.
✌️
MBWorld Fanatic!
Joined: Feb 2014
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From: MA
2008 E350 4Matic, 2011 E350 4matic
There are wires coming out of the oxygen sensor so you need a special socket that had a slice in the side so the wires aren't cut. Otherwise there's nowhere for the wires to go when you put a regular socket on top of the oxygen sensor. Because it's an exhaust part, sometimes it can be hard to access and sometimes it's hard to loosen them because the heat has baked them on. But the new ones should already have some kind of grease on the threads so they can be changed out at a future date. As mentioned you only need to do the two upstream sensors. They're basically getting the raw exhaust before the converter so they do the most switching and wear out over time. The downstream ones don't really do much, they just monitor the results of the catalytic converter and the exhaust is cleaned up by the converter so they don't do as much work and don't normally wear out. When the upstream and the downstream have the same results, the computer knows that the converters are shot because they're not doing anything. You can sometimes rent the socket for free from various auto parts store like Autozone or O'Reilly Auto parts. You only change them out in the 100k range although the maker of the sensors say about 60-90k.
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Joined: Feb 2014
Posts: 6,190
Likes: 1,550
From: MA
2008 E350 4Matic, 2011 E350 4matic
No, that would be a real nightmare. Usually the exhaust bolts are rusted on and if you had to remove them, you'd have to get new bolts. They're just in an awkward space because the upstream are just before the catalytic converters and the downstream are the ones after the converter. Haven't done them on your particular car so don't know how hard it is to reach them. Sometimes depending on the space you can get at them from the top of the car, sometimes you have to get at them from the bottom of the car.
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Member
Joined: Dec 2021
Posts: 144
Likes: 72
From: Calverton MD 20705
2013 W212 E350 RWD
Hello, what led you to determine that you need new oxygen sensors? Are you getting a P0420? If so, let me know if that solves your problem.
Member
Joined: Dec 2021
Posts: 144
Likes: 72
From: Calverton MD 20705
2013 W212 E350 RWD
There are wires coming out of the oxygen sensor so you need a special socket that had a slice in the side so the wires aren't cut. Otherwise there's nowhere for the wires to go when you put a regular socket on top of the oxygen sensor. Because it's an exhaust part, sometimes it can be hard to access and sometimes it's hard to loosen them because the heat has baked them on. But the new ones should already have some kind of grease on the threads so they can be changed out at a future date. As mentioned you only need to do the two upstream sensors. They're basically getting the raw exhaust before the converter so they do the most switching and wear out over time. The downstream ones don't really do much, they just monitor the results of the catalytic converter and the exhaust is cleaned up by the converter so they don't do as much work and don't normally wear out. When the upstream and the downstream have the same results, the computer knows that the converters are shot because they're not doing anything. You can sometimes rent the socket for free from various auto parts store like Autozone or O'Reilly Auto parts. You only change them out in the 100k range although the maker of the sensors say about 60-90k.
You're talking about a crowsfoot socket, right?
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Joined: Feb 2014
Posts: 6,190
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From: MA
2008 E350 4Matic, 2011 E350 4matic
As for the socket, a crowfoot wrench would also work. Normally it's just a socket with the slice in the side so the wires can stick out. Autozone has a free loaner program so you don't even need to buy the socket/wrench just calls for a 30 deposit and you get it back when you return it.
https://www.autozone.com/test-scan-a...et/1103591_0_0
https://www.autozone.com/test-scan-a...ner/948079_0_0
