MAF code

This sounds like you have a dirty throttle bore, here is a guide that will help you fix the problem. Also, can you remove the MAF connector to see if there is any corrosion or damage?

https://www.2carpros.com/articles/throttle-actuator-service

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

What is the actual code? There are a couple things about diesel engines that will cause this.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

However, we need to know the code so that we can be sure this is the same thing that I am thinking it is.

Basically, what happens on these is the manifold gets soot in it and it is restricted so the PCM thinks there is a MAF sensor issue, but it just can't breathe.

So, cleaning the EGR is a good thing but more than likely there is already soot in the intake and that is going to have to be cleaned as well.

Perfect. Yes. These codes indicate restricted air flow. So, what I would do is remove the tube from the turbo to the intake and see if there is any build up.

Yes. Soot is the natural byproduct of diesel engine combustion. If you remember the black smoke that diesel trucks use to emit, this is soot. So now all that needs to be captured but it gets into the EGR system and eventually can get into the intake, and it will restrict the intake.

Take a look at the info below and let's start with the first code and check the things listed in the action in service section.

Okay. I agree, however, seeing what is in that hose will be telling as to what the issue is. To answer your question, yes, it is rare that it is just the hose but that will be a sign as to what is going on.

If you find soot, there then you will have more in the intake and that is going to restrict the air flow and make the PCM think the MAF is just wrong.

Basically, the engine can't tell that there is soot build up causing a restriction, so it thinks that the MAF is wrong.

So that code does not tell you where the restriction is only that the MAF is showing low air flow. Just experience with diesel engines is what tells us that this is likely the cause.

Haha. Yeah. I am not sure as I have not done that on these vehicles but it is a BMW so I would bet it is.

I am attaching the info on this but there is a good amount of detail on cleaning the intake system and plenum so clearly BMW is aware of the need to do this. I am thinking that the swirl valve are going to be the root cause of this. When they get covered in soot, they stick and will restrict the air flow as well. If this is the case, the entire intake needs to be cleaned.

BMW says to use a wand to reach down the intake and you basically media blast the engine clean.

When it is running does it seem to have full power? I am thinking the exhaust may be clogged.

Is the boot between the MAF and the throttle bore in good shape? No leaks?