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Bosch: LMM (Air Mass Sensor) Technical Support Statement

 
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MadMick
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Post12-10-2003, 9:55    Subject: Bosch: LMM (Air Mass Sensor) Technical Support Statement Quote

Hello everyone.
After experiencing the problem with my LMM (as described below), and having tried to find a cheap solution (a single sensor on eBay), I called Bosch's technical customer service.
A very kind and knowledgeable man explained to me that they were aware of the problem. Over time, small particles can become embedded in the sensor surface and affect the readings (nothing new). When I asked about the individual sensors, he explained the manufacturing process: The mass flow sensors are attached to the corresponding pipe fitting at the end of the manufacturing process (now it gets interesting). Each individual sensor is then calibrated, zeroed, and programmed and encoded according to the manufacturer's specifications using a flow bench. This is what makes the manufacturing process so expensive because this process is performed individually for each mass flow sensor.
Individual sensors may or may not be working, just like in my case.
It probably doesn't make much sense to try to save money there.
In the latest issue of Autobild, there's a report about this VAG problem, and VW is opening up its goodwill policy regarding it. I'm going to visit my VW dealer and hope for a solution under the goodwill program.
Best regards,
Mick.


Translated on 01-10-2026, 17:37.
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diesel.gustav
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Post12-10-2003, 15:19    Subject: Bosch: LMM (Air Mass Sensor) Technical Support Statement Quote

Deleted upon request.


Translated on 01-10-2026, 17:38.
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Dan.jel
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Post12-10-2003, 19:19    Subject: Bosch: LMM (Air Mass Sensor) Technical Support Statement Quote

Whether it's a 5mm or 6mm hexagon Torx, it doesn't matter to my fine pipe wrench! icon_lol.gif

When I was working on the ARL (presumably a piece of equipment), I just used a 5-point star bit and a 6-point Torx bit because they are the same size...


Translated on 01-10-2026, 17:39.
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ulf
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Post12-10-2003, 20:01    Subject: Bosch: LMM (Air Mass Sensor) Technical Support Statement Quote

diesel.gustav wrote:
Each sensor element is calibrated to the specific flow rate in its corresponding pipe. Therefore, replacing a sensor element is not recommended and would be considered a substandard repair.

Hello Gustav,

If the wonderful factory calibration is already so compromised by insufficient long-term stability that, in an otherwise perfectly sound engine, under normal operating conditions and at full load, the soot limiter starts to engage as early as 3500 rpm... (I personally measured this with VAGCOM on a 90 hp Golf 4 Syncro).
"...in my opinion, this is a kind of blatant overpricing and shoddy mass production from the factory, and replacing the sensor element only results in another (hopefully with slightly less egregious!) instance of shoddy workmanship."
Gruß Ulf
_________

MG4 Electric


Translated on 01-10-2026, 17:40.
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christians
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Post12-10-2003, 20:47    Subject: Bosch: LMM (Air Mass Sensor) Technical Support Statement Quote

Hi,
What would be the measurement error if an unsuitable sensor were used?
What is the purpose of real-time flow measurement with the capture of unsteady flow components? Couldn't errors caused by averaging through a slow sensor be compensated for using a characteristic curve?
Gruß Christian
A6 BPP, Ex-A6 AKN (Gurke), Ex-Audi100 92 AAT (5Zyl.)


Translated on 01-10-2026, 17:41.
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