Dont rely on AI for such information.
Use Xentry, because MB of W212 uses different oxygen sensors type since 2009 to face lift and depending on engine type.

The proper ID of oxygen sensor would be Bank and then sensor number/position....if using OBD2 device or scanner in OBD2 mode.
B1/S1 = Bank 1 , upstream wide band Lambda sensor.
B1/S2 = Bank 1, downstream narrow band oxygen sensor.

If OBD2 type scanner, often the may not produce accurate reading for upstream/front wide band sensor, which is a processed data from ECM and not directly from
the lambda sensor itself.

The current pumped into the Lambda sensor is actually the rich and lean value, and some ECM does not produce this value for our viewing, instead it will give us the
Lamda value, which is most important.

Attached is Bosch wide band LSU4.9 which my engine uses


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Here is Xentry values.

Cold start is Open Loop, so no feed back from oxygen sensors. ECM does not use any oxygen sensors to determine fueling quantity. It uses its internal memory.


.

Engine already warming up and now the oxygen sensors are being used by ECM for fueling quantity.




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Xentry does not have FUEL TRIM data.
FUEL TRIM data is OBD2 stuff.

Lambda value above or below 1.0 is where fuel trim comes from.
But becareful when looking at Lambda value vs fuel trim.
Lambda value tells you engine conmbustion is Lean or Rich.
Fuel trim is telling us what % of extra fuel is taken out or added to the fueling of the injectors at that point in time if short trim and what compensation value is added if long term.

If we mesh the throttle to do WOT or let go during de-acceleration, the engine will be open loop and not closed loop.






If anyone wants their engine to be super nice for driveability, replace all 4 oxygen sensors every 10 years or 100,000KM.
These sensors get "slow" as they age. They live in the 2nd most hostile location of the engine, which is the combustion gas flow.
Only spark plugs and injector suffer 1 level worse working environment, the heart of the explosion of combustion.

I replaced mine already, all 4 oxygen sensor and very nice result. I am only at 43,000KM and was under 40,000KM when I replaced all 4 oxygen sensors.
My rear oxygen sensors got lazy.

 

The CEL went off today about halfway through a new tank of gas. It still has the stored CEL but the light is not on. Here are the three data points with the most current from today in green. What is going on?

 

Something has caused your engine passenger side bank to run normally again....


banks are nearly balanced again

Fuel Trims + Temps are balanced again now your V6 has normal power.
You did not "Italian tune-up" through this so your engine stayed unarmed.

You realize this has nothing to do with exhaust cats and everything to do with combustions.

Now you can troubleshoot the engine fuel mixture.

Use your scanner to check the fuel pressures at idle and under load...

Fuel would affect BOTH banks equally so something else is causing this...
a serious AIR leak: failing PCV feeding crankcase pressure.

"More air" precisely calls for Richer trims...

 

As stated above, I also recently replaced all four sensors after noticing that my downstream sensor was reacting improperly. When looking at the graphs, the sensor was making dips not attributed to throttle input. Meaning the upstream sensor reacted to new air but the downstream did not act the same. In an overlayed graph of upstream and down stream, upon blipping the throttle you should see a slight delay in the DS (downstream) sensor reacting to the input. And obviously both left and right sensor graphs should overlay each other.

Since I was in there, I did not just replace the one bank. I replaced all four sensors, and the graphs lined up nearly perfectly again and reacted symmetrically with just a small deviation because of small upstream variability in fuel, cam position adaption, etc as Cali mentioned.

search with keyword lambda under my name in the 212 Amg forums to see my pics. I did this about six weeks ago or so….. here it is.

https://mbworld.org/forums/w212-amg/915750-lambda-control.html#post9198592

 

to that end we note CERATEC was involved in contaminating your exhaust. It's a good product but high ceramics content comes with side-effects.

Ppl who are forced to top-off Quarts of "missing engine oil" should consider early Lambda replacement: such as 80k.Mi instead of 110k.Mi.
Oil hydro-carbon readily burn with fuel combustion but not the solids that go right out the exhaust.

Waiting for exhaust sensors faults is not the way to go. Lean engines combustions run hotter than evenly balanced trims: that's what is best.

 

yes, not to be off-topic but Ceratec clogged my piston rings and created deposits through the exhaust cycle. Since I’ve done all my cleaning, I’ve not had so much of a puff of smoke on startup or acceleration and the rear end is seeming to stay cleaner.

 

My M272 has a little over 160,000 miles and had to replace the upstream O2 sensor last fall due to a shop damaging it. Thats a story in itself. If I had to bet id say they are the original sensors. It looked pretty good to me, cleaner than I expected it to look. Im sure you cant go on looks alone though.

Replaced it with Bosch brand it its been working great.

 

Tim your used sensor looks extremely clean for being a 160kMi old original Lambda...

What are chances the heating element could survive for that many heat cycles??

What sort of driving do you do with your M272: city/Hwy?

 

Are O2 sensors considered a wear item?

 

yes, just like plugs, tires and brakes.

Oxygen sensors are the old type downstream
Lambda are the wideband sensor upstream
They work differently but look very similar.

Reliable for 70k to 100k in US driving conditions.
Canada may see more issues from the sensor heater circuits ??

 

Looks great for that mileage. The sensors shown in my thread were original with only 73k.

 

So the Mercedes specialist today concluded my bank 1 LTFT sensor was bad and they replaced it. I have driven about 40 miles since, but the LTFT is still at 10.9%. I know this is an average (distance or time?), but how long until it recalculates? Also, there is still a stored error code for the LTFT Bk 1 sensor. Will that delete after the LTFT Bk 1 sensor recalculates?

 

Fuel trims are recalculated hundreds of time per second... live!
The actual fuel trim is the combination of Long term + Short term.

it's hard to tell what parts your specialist is gonna want to replace next....couple new injectors would not be too far fetched.

The other bank lambda should be replaced to match exhaust sensing.

 

I plan to change the sensors on bank 2 when funds allow. I was under the impression that a stored error code needs to be cleared, as it will not clear by itself. I assume they did not clear this code. I also expected the ECU to be reset when the new O2 sensors were installed. Does the LTFT sensor use an average of time or distance ?

 

Dealing with the application of fault codes can be a mixed bag....
The best is zero code live or stored.

Stored codes can be transient or marking system disfunction.

Stay focused to get both LTFT low & nearly equal.

This "Stored fault" clearly do not cause that issue.
The engine itself is causing that LTFT value. Not the ECU gone wild.

 

I am going to drive it for a few days to see if the LTFT Bk 1 number evens out. It is my understanding this is an average and this is why the LTFT number does not change frequently like the STFT number does. Since the old data was not deleted when the new sensor was installed then it must be being used to calculate the current LTFT average. What I don't know is how much data is saved to calculate the LTFT average.