good job

Update: Still having issues with the mass air flow drift, even after resetting all adaptations. I am mostly getting code 2624-001 - Mass air flow sensor Sensor drift Offset drift under engine load The limit value of load point 1 has been exceeded.

I did get similar code 2633-001 one time: Mass air flow sensor Sensor drift Offset drift under engine load The limit value of load point 2 has been exceeded.

I suspect a leak somewhere but I am not seeing anything obvious. Given the code, is it likely to be on the suction or pressure side of the intake system?

Also, I have a Foxwell NT510 but I am unable to find readings for these adaptations anywhere. Am I missing something or is this Xentry only data? What exactly are the load points mentioned in the codes?

Beware the cheap sensor, it may be lying to you...there is a reason it was only $40, the legit MB bat wing with 2 legit sensors is almost $500 IIRC

I'm in agreement with JayBob. Don't try to save money by purchasing after market mass air flow sensors.

I have not replaced the MAF sensors. They are likely original.

I did find a cheap Bosch O2 sensor online and replaced it. It looked real to me and my O2 code has not come back since, so I am feeling pretty good about it.

I suspect an air leak somewhere... just trying to understand what drives the code to help narrow my search. Intake side, turbo side, seeing too much vs too little air... all would help focus on likely causes.

Ah misunderstood on the MAF vs O2 sensors. If you are running original MAF sensors it’s probably time for replacement. But yes, look for an air leak first…

Tiny shots of WD-40 on a suspected leak point will make the engine speed up slightly, don’t go crazy with it but a little should sniff it out.

I have been noticing some belt shavings all around the tensioner. It has been going on for a while so I decided to investigate today. All looked good until I started the engine. The tensioner is wobbling at idle - assume it is much worse at higher RPM. Looks like a tensioner replacement is needed, huh? Oddly, the tensioner and belt were the last things the previous owner paid to have replaced in March 2021, less than 15k miles ago, for almost $900!

https://youtube.com/shorts/K_F7m-7og8c?feature=share

Back for another update. I have been distracted for a while but getting this stupid check engine light off has becomes a priority. Codes have been consistent for MAF drift under load + upstream O2 sensor. Last week I bought a new set of gaskets/o-rings for the turbo inlet and outlet pipe. I also cleaned the EGR pipe where it hits the throttle body (not too clogged) and replaced those gaskets.

The CEL continues after a bit of driving but it seems to be throwing only the O2 sensor code: 3149-008: Characteristics of NOx storage catalytic converter Oxygen sensor upstream of NOx storage catalytic converter (negative signal edge)

This makes me think the O2 sensor may be bad, so I have ordered a Bosch replacement. Oddly, I find no other mention of that code on the internet. Not on the Benz or Sprinter forums. Does anyone know exactly what it means? I am tempted to pay for Alldata or similar to see if it lists common causes. Or maybe the second "new" sensor in a year will fix it. Time will tell!

I installed a Bosch 17236 sensor from a reputable online retailer and so far so good. The old sensor was covered in soot with only 5k miles since replacement. I am thinking the MAF drift codes may have resulted in a rich condition that clogged the O2 sensor. Or my engine is in such bad shape that it is burning a ton of oil, though it never smokes and has MB diesel spec oil. I have not seen the drift code since replacing a bunch of seals around the intake so it is possible that I have addressed all the problems - fingers crossed!

You can't tell if it is burning oil yet or not?

Another update:
The CEL kept coming back so I decided to get a pro involved - took the car to Bertini's European Service Center in The Woodlands (Houston). They checked everything over and the computer said everything was working properly, no boost leaks, etc. They did see an engine software update available and recommended doing that before anything else. I was skeptical, but went ahead and sure enough, no CEL since. The car definitely drives/shifts differently now, especially when cold. It holds RPM's higher. Regardless, it seems to have fixed the CEL.

I am now chasing mild to moderate oil consumption and believe it is the PCV adapter housing. I replaced the PCV itself but did not touch the adapter. The adapter o-ring has a small external leak and I suspect the interior gasket/face around the camshaft is worn as well. That could be leading to some oil consumption via the PCV system. It is the part shown at 5:30 in this video:
https://www.youtube.com/watch?v=IoMXqaBMO6k

This is an old thread but my foxwell scanner, sold as updated and supported, IS NOT updated or supported. I was just a the website and told I must buy a new scanner, no updates.
For this reason Id suggest any scanner but foxwell. And Im not relying on ad copy, I want to know from users which one to buy to work on my just acquired sprinter 4 cylinder.

I'd look in to what Autel has to offer.