Clean LMM: How to Clean Your LMM.

'I had problems with the mass airflow sensor (MAF) in my 1Z engine in my T3. The diagnostic tool showed an error code for the MAF. The whole thing was quite oily. I sprayed it with WD40 and then rinsed it with water. The error is now gone, and the engine starts normally again.'

Are there better cleaning methods?

Hello Joe,

What error code did the control unit display?

Okay, a different question: How do you actually remove that thing? I've wanted to clean the mass airflow sensor (MAF) before, but I can't seem to get the housing cover off.

Can I pry it open with a small screwdriver, or is there an easier way?
I can't reach it without expanding the structure; there's a net in the way.

(Passat 35i engine, model 1Z)

To the best of my knowledge:
- Mass flow meter measuring unit that can be detached from the LMM housing.
- LMM measurement device and housing, one component.
For design type 2, it seems you can only clean it from the back using a spray nozzle (e.g., brake cleaner), as the rear grid has a larger mesh size.

Best regards, Rainer.

Hi,

I just logged in, and I'm new here.

I really like your website.

I drive a BMW 530d (tuned by HOPA), not a TDI, but I occasionally experience 'magic' with the mass airflow sensor.

Joe wrote that he cleaned his LMM with WD-40, but that's a general-purpose oil!

At 200°C operating temperature, this should either burn into the LMM (Lambda Measuring Module) or at least create a layer that 'insulates' it. As a result, it shouldn't be able to measure correctly anymore, right?

So far, I've only dared to use alcohol and cotton balls. It's helped, at least.

What is the best cleaning product?

It looked to me like there was a clear coat of lacquer over the small, soldered-in pin on the heating element. Will this be damaged by thinner or similar solvents?

Thank you for all the answers.
research

Hello,

Since the mass airflow sensor (MAF) is installed directly after the air filter housing, as it is for everyone else (I believe), I find it unlikely that temperatures of around 200 degrees Celsius would be present there. However, I am open to being corrected.

Mine has now been driven for approximately 154,000 kilometers without a faulty mass airflow sensor. What do you think?
I need to clean it, just as a precaution (who came up with that word?).
oder soll ich warten bis ich wieder vom Urlaub zurück bin? Sure, here's the translation:

'Net, that's it.'
There's absolutely no more room on the highway.

Thank you, Mike.

It doesn't usually get dirty overnight. There's only one saying I know for that:

Never touch a running system.

Quote:

Since the mass airflow sensor (MAF) is installed directly after the air filter box, as it is in most other cases (I believe), I find it unlikely that temperatures of around 200 degrees Celsius would be present there. However, I am open to being corrected. Mine has now been driven for approximately 154,000 kilometers without a faulty mass airflow sensor. What do you think? I need to clean it, just as a precaution (who came up with that word?). oder soll ich warten bis ich wieder vom Urlaub zurück bin? Sure, here's the translation: "Net, that's it." on the highway, absolutely nothing more is possible.

Hi.

Since the mass flow meter (MFM) heats itself and uses the cooling effect of the airflow as a measure of the mass flow rate, there must be significantly elevated temperatures at the MFM. Unfortunately, I don't know exactly how much .

Since any cleaning process carries a certain risk of causing damage, I would only recommend it if there's already a noticeable performance loss due to the mass airflow sensor.
Then, carefully remove it, spray the small ceramic measuring plate with brake cleaner, let it dry, and reinstall it.

Multipurpose oil on the sensor is likely to provide a small amount of heat insulation, which could result in reduced temperature readings and, consequently, a loss of performance.

Hello everyone,

To clean the mass airflow sensor (MAF), you can also use a cleaning agent (contact cleaner) specifically designed for electronics.
While I don't want to make this a blatant advertisement, I use this product almost every day, for both standard printed circuit boards and ceramic circuit boards.
This product is grease-dissolving, cleans thoroughly without leaving residue, and does not damage most plastics.
This spray can has a nozzle that allows you to reach even hard-to-reach areas.
Regarding the LMM (likely referring to a Mass Air Flow sensor) preheating, I can only say that the sensor heats up significantly (glows) after the vehicle is turned off, in order to burn off any potential contaminants.


Regards,
Gerhard.

"...'freibrennen' only applies to hot-wire sensors. The one installed in TDIs is called a hot-film air mass sensor."
Function, see link https://community.dieselschrauber.org/en/viewtopic.php?t=3347

Best regards, Rainer.

Thank you, guys!

So, the diagnostic tool showed error code 553 on my device.

It was also clear to me that no residue should be left behind after cleaning, which is why I also rinsed it with a gentle stream of lukewarm water (not too strong, just from the sink).

Yesterday, I cleaned my mass airflow sensor (MAF) because my air-fuel ratio seemed very low, and the flow times were around 10 seconds.

I removed the sensor from the pipe and used a spray gun with a diluted cleaning solution to blow it clean. (There were oily dust particles on it). The airflow also helps to dry it immediately.

It's running much better and faster now! However, please proceed with caution and at your own risk if you try to replicate this.