BMW F04 ACTIVE HYBRID7 Difficult! Air mass validity ''101F01''


・Drivetrain warning display

・Engine check light on

In stock at.

This blog seems to be a little long.

There are no engine problems at all so far.

I'll try to diagnose it right away.

Error code ''101F01'' Air mass system validity

came out.

This error code, which has no malfunction pattern, is extremely troublesome.

Reconnect to BMW genuine diagnostic system ISTA.

CHECK the data values

I will briefly explain what the problem is.

Below is a diagram of the intake system for the N55 engine.

The intake system has a large number of temperature sensors and

A pressure sensor type is installed.

Air mass sensor number 6 first measures the intake air amount of the engine.

Intake air flows through the piping shown in the image to the intake manifold.

For the air amount calculated in step ⑥, the downstream intake manifold

This means that the calculated amount of air is too large.

``101F01'' Possible failure points regarding air mass system validity are:

・Excess air (secondary air) is being sucked in from somewhere

・Discrepancies or malfunctions in the measured values ​​of each sensor

・Defective throttle butterfly

・Carbon accumulation around the intake valve

・Crankcase ventilation abnormality

・Turbocharger boost control system error

・Valvetronic related failure

・and more..and more...

There are so many different types that it can be difficult to narrow it down.

It would be better if engine malfunction was the symptom.

This time it was a pattern with no symptoms.

There's no use worrying about it, so let's go!

First of all, the most suspicious

・Excess air (secondary air) is being sucked in from somewhere

Let's focus on.

Visually inspect the intake system.

Then, ah, vacuum pipe!

Can't you just slip through it?

This is where I was breathing air.

Easy solution! !

I feel that way. Until this time.

It looks like the connecting rubber hose has shrunk and fallen out due to aging.

Replacing ASSY parts is good, but there is no problem with the pipe part.

Replace only the connection hose using stock parts.

Secure it with a hose band so it doesn't come off and do a road test.

This ends! That's what I thought~

Coming again. Back to square one...

I regain my composure.

Check the intake system for leaks using a smoke tester.

The structure is similar to electronic cigarettes or VAPE.

Pour this into the sealed intake system.

If there is a place where secondary air is being sucked in, smoke will come out from there.

Oops, I found a leak!

It's hard to tell from the photo, but smoke is leaking out from the joints of the pipes.

This is after passing through the intercooler.

If the turbine is pressurized, air leakage will occur.

Stop leaks by replacing the hose band! And road test!

What do you think?

Come again..

I'm disappointed, but this

・Excess air (secondary air) is being sucked in from somewhere

Since this possibility has been eliminated, let's move on to the next step.

I will remove and check the parts that can be visually confirmed.

Throttle butterfly, very beautiful. There are no problems with movement.

Intake valve condition

It doesn't seem like the carbon accumulation is bad enough to cause problems.

If the carbon is bad, walnut blast cleaning is required.

・Defective throttle butterfly

・Carbon accumulation around the intake valve

These were also considered normal and were destroyed.


・Discrepancies or malfunctions in the measured values ​​of each sensor

Would you like to try this?

Several pressure sensors are installed in the intake line.

Since these are the same parts, you can replace them and check them.

This is called a cross check.

If the sensor value is incorrect, the deviated value will be transferred to the replaced location.

Try replacing the sensor and see how the values ​​change.

Please look below. This is the idling value.

BMW's gasoline engine is controlled by Valvetronic mechanism.

The throttle body is almost always open and there is almost no negative pressure.

The two above are the sensor values ​​in front of the intake manifold.

Since the atmospheric pressure is 1013.25hpa, this means that it is detecting atmospheric pressure.

Only the pressure in the intake pipe (intake manifold) is a little low.

This is because the pressure changes slightly depending on the opening of the throttle butterfly.

So what happens if you stop the engine?

Let's take a look.

All sensors are displaying atmospheric pressure.

This value does not change even if the sensor is replaced.

That means

All pressure sensors were determined to be normal.

Then there is one sensor that seems suspicious.

When I first diagnosed it, I found that the air mass value was a little low.

If air is being sucked in secondarily, the air mass value will decrease.

That's actually the reason why we started crushing the secondary air inflow first.

There is a strong suspicion that the air mass value fluctuates or is unstable.

After diagnosing this far and narrowing down the problem area,

This sensor currently seems to have the highest possibility of failure.

After consultation, we decided to replace the air mass sensor first.

Of course, replacement does not necessarily guarantee improvement.

In order to keep costs down, we use manufacturer's OEM parts instead of genuine parts.

The item itself is the same, only there is no genuine part number stamped on it.

Replace quickly

Road test..

Did it! Error resolved!

The air mass value, which was low, has been calculated to be almost normal.

Finally with this

The calculated air volume was too low due to a malfunction of the air mass sensor.

It turned out that an air mass validity error had occurred!


Diagnostic machines are very convenient! but

This does not mean that you can quickly find the faulty part.

It is just one of the "auxiliary" tools.

Humans must repeat the process and search for failures.

Of course, there are also simple repairs that can be quickly answered using a diagnostic machine.

However, as in this case, it takes a considerable amount of time to narrow down the location of the failure.

There is actually quite a lot of work involved.

However, if you blindly replace parts based on your intuition or experience,

Not only does it cost more, but most of the time it doesn't heal, so it's a painful experience lol

At our store, we make full use of various diagnostic machines, testers, wiring diagrams, data values, etc.

We always strive to provide diagnosis and proposals that narrow down the failure location as much as possible.

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