Gang,

The beauty of having a proper full time data logging using my Banks iGauge Data Monster......... is such a benefit

Here is a slow rear or downstream oxygen sensor BANK 2 but only slow-dumb-azz at idling and decent but not great at normal cruise speed.
I like replacing components when they are not 100% doing its proper duty. I do not wait for DTC.
CATs are VERY expensive and poor performing oxygen sensors can ruin my CATs.

This is from one of my log of approx 2 hours run, out of a 9+ hours run of non stop Jakarta to Surabaya city.
To be exact, it is the 6th hour and up engine run time at approx 500ish KM travelled. So basically the car engine has clear all carbon yada yada.
Per 200KM I will re-fuel and take a wee-wee. 98 RON octane is not available is all petrol stations, hence I choose well where to refuel.

For Bosch narrow-band oxygen sensor our W212 gasoline rear sensors ( Bank 1 and 2 sensor #2 or after CATs ) , 0.5 Volts and higher is RICH.
https://www.boschautoparts.com/docum...ech%20Tips.pdf








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===========================================******* ****======================









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Because my Bank 2 downstream 02 sensor or #2 sensor is falsely reading RICH, the fuel trim then goes NEGATIVE quite high, as seen on 2nd graph below.





NOTE : My engine coding I saw at the ECM is on purpose set at SLIGHT RICH, don't ask me why. I guess to compensate for a non 5-star fuel Indonesia has back in 2014.
Only in 2020 officially my country fuel is at Euro 4 compliant spec ( 15 years too late LOL ) and before that it was Euro 2 grade. Europe today is Euro 6
My E400 is a Euro 4 spec as per data card.
So 2014 to 2020 basically its been "poisoned" by sub-standard fuel

Typical LONG TERM fuel trim would be maximum -6 to -7% because I am a lead footed driver. A polite driver with an-egg-at-throttle-pedal-attitude would do better like -4% or overall better than mine.

=================The legal framework consists in a series of directives, each amendments to the 1970 Directive 70/220/EEC.[5] The following is a summary list of the standards, when they come into force, what they apply to, and which EU directives provide the definition of the standard.

• Euro 1 (1992):
  • For passenger cars—91/441/EEC.[6]
  • Also for passenger cars and light lorries—93/59/EEC.
• Euro 2 (1996) for passenger cars—94/12/EC (& 96/69/EC)
  • For motorcycle—2002/51/EC (row A)[7]—2006/120/EC
• Euro 3 (2000) for any vehicle—98/69/EC[8]
  • For motorcycle—2002/51/EC (row B)[7]—2006/120/EC
• Euro 4 (2005) for any vehicle—98/69/EC (& 2002/80/EC)
• Euro 5 (2009) for light passenger and commercial vehicles—715/2007/EC[9]
• Euro 6 (2014) for light passenger and commercial vehicles—459/2012/EC[10] and 2016/646/EU[11]
• Euro 7 (probably 2025)[12]

These limits supersede the original directive on emission limits 70/220/EEC.


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I once check MB branded Bosch oxygen sensors front and rear at MB Indonesia they sell almost 300% compared to BOSCH OE.... This I can not tolerate !!!!

So I ordered from FCP Euro, just like my in-tank my fuel filter. I ordered all 4, they are all 9 years old 38,000KM and my country fuel is not the best, so oxygen sensors are rather short lived.
My Ford Fiesta oxygen sensor, I think up-stream one and I do not remember if it is WideBand or NarrowBand ?.............. issued a DTC within under 20,000KM and 9 years old....LOL.



Damn, so cheap !!! Add 25% import duty when landed, still is CHEAP !!!!
MB Indonesia throat slayer strategy for certain items is truly SCARRY !!!!
MB Indonesia sold Mobil 1 0-40W at 180-200% market price I can get from Mobil Indonesia official on-line store...DUGGHH !!!




Since I will be doing my propeller shaft rubber boot and middle bearing replacement : https://mbworld.org/forums/e-class-w...ml#post8822118
and exhaust system must come down a 100%, might as well replace ALL 4 oxygen sensors while at it.

I will report in 45 days soonest for the result when and if all 4 oxygen sensors are replaced.

 

Replacing both primary sensors routinely is one of the smartest thing I know. I was just preaching this yesterday to my nefew who drives a V6 Acura and dreams of BMW.

The lambda sensors drives the engine fuel map. There is nothing more important for good engine response and driveability.

A lazy plugged up slow lambda is not going to set any code. It's only going to de-tune the injection to what the sensor say can be burned.
Lean engine makes for poor accelerations with additional heat generated.

When the engine is de-tuned both banks are no longer trimmed equally... that throughs the engine out of balance... more vibrations, less output power. More throttle... more heat!

I used to wrongly believe the O2 fault code was the signal to replace them. Nop, WAY TO LATE when O2 ceramic heater gives up!!
The extra heat generated by running an engine lean is a killer.
I think if you replace primaries between 75 to 120kMi or earlier it's a very smart move. To diagnose these sensors compare both LTFT. Extreme LEAN forces combustion to weak misfire territory.

 

When I pushed hard the engine, the CAT or oxygen sensors can register 900ish celcius and poor thing they are....., will die faster too.
Even the motorsports version LSU4.9 wideband is advised with 500 engine hours limit but at racing pace of-course.

These sensors are consumable, albeit quite a long time or decent mileage.

 

While needing to remove the exhaust system a 100% due the propeller shaft rubber boot replacement, as told here : https://mbworld.org/forums/e-class-w...ml#post8835941


All 4 AFR and Oxygen sensors got replaced. Sweet.

01. When you do this, make sure buy new exhaust bolts. Only 4 pcs for both sides, 2 + 2.
They due to 900C plus operation will "rust". Before they break and cause grieve, best to replace them every time you remove your CAT.








Inside the CAT







I do not know if this is for M276 3.0 Turbo only, or also for all of W212 with 3 liter and above engine.


The CAT honey comb are actually 2, not one single piece.






This is boroscope inserted to 2nd or downstream oxygen sensor hole.


Look Ma, 2 honey combs



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The rear oxygen sensors on my car is by NTK, not Bosch.
The front AFR sensor is Bosch




Rear oxygen sensor is simple 0.1 to 0.9 volt switching type NARROW BAND, so brand is not important as long as they are reputable one like Bosch and NTK or Denso.
It has to be the 450millivolts as STOICH or 14.7 AFR if gasoline.




The front AFR ( Air Fuel Ratio ) sensor or Lambda or Wide band Oxygen Sensor..... many names, and it is not a simple NARROW BAND switching type sensor like the rear one.
This one you can not make a mistake. Brand to brand their working is not the same. You must buy what Mercedes uses and it is by Bosch and the correct type.
The ECM we use, has software to work with a specific AFR appointed to the engine type & variant and even the heater strategy is crucial to the longevity and fast operational readiness of AFR.
So, don't F around and try to save small money like US$50 or so and use aftermarket bullshi-et brand and model.
I do not want to explain how it works as it is rather complex, all I can say is that it is unique and only a scan tool ( best is using Xentry ) to be able to read the value correctly.
You can't scope or use DMM for this AFR. Scan tool only, that is the challenge.

Here is if you want to read : W212 engine if M276 and M278 is using the Bosch the LSU 4.9 .
I attached one document explaining difference between LSU 4.2 and 4.9 by someone and 1 tech document from Bosch.

Data sheet by Bosch : https://www.bosch-motorsport.com/con...or_LSU_4.9.pdf













Physical conditions of the ones from my engine. 39,000KM old and 9 years. Front AFR




Will update the Long Term fuel trim values when I drive the car enough to have a decent data...................

 

After reading this thread i did swap also new lambdas in. M278 CLS 500 SB, 2015. Mods to have 707hp. Very many dynosessions, years of Dragy pulls, etc. abuse.
Car driven 180 000km ( about 120 000miles). Near 9 year old stock lambdas.

I did feel the same results as S-Prihadi have told in two his topic and I think even more. Car runs now so smooth, no need to press the gas pedal so much, idle vibrations gone, shifting seems better. Like car is now more a live. I didnt expect these results. The walnut blasting did help a really lot and now this. Really cool.

Here are pics what my beaten up lambdas did look like.

 

Wow, 180K KM, that is so good already if you are heavy throttle foot
Your sensors surely looks abused. It does seems the AFR setting is rich , by the black soot, perhaps part of the MOD.
Good to know the improvement.

Thank you for sharing......