# TT225 MAF sensor specifications



## [email protected] (Jul 1, 2009)

We have a number of customers running our F23 turbo product in their TT225s, and while tuning them we always have to be mindful of the subtle differences between the early model year cars and the later ones. The North American market TT225 was introduced with an AMU engine code equipped with a narrow-band air/fuel mixture system, which was not replaced until introduction of the BEA engine code cars in 2003. This changeover involved new oxygen sensors, new higher data rate ECUs & a new MAF sensor specification. I wanted to post some details on just the MAFs, since I've seen people ask which one they have or should buy. Both cars have a 3" housing, but the sensors within differ. Here are some pictures:

Narrow-band AMU engine sensor, part number F 00C 2G2 040:











And here is its counterpart from the later, wide-band BEA engines, part number F 00C 2G2 047:











The last three digits in the part numbers DO make a difference. If you look at the MAF airflow scaling maps compared, you will see that the earlier sensor had a narrower measurement gamut, and is "soaked" with 5v of output at around 250g/s:











As you can see, these sensors are not interchangeable, and on the less-sophisticated AMU engines, it's important to run the correct sensor. The BEA sensor is able to register another 20 or so grams/second, which is helpful for tuning a larger turbo. But in our experience neither sensor in its stock housing is up to the task of metering effectively for our F23. The hybrid turbo's airflows can easily exceed 270g/s, so we have moved to incorporation of the larger MAF housing from the R32 engine. It delivers 18% additional measurement capacity when paired with either of these sensors, and our tuning partners Motoza Performance & Eurodyne both offer the correct mapping for this modification. Here is a look at the measurement scaling of the larger housing versus the two originals:










Thx


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