My sensor has gone MIA. will my original 471 sensor work for the S3 conversion? I still have the housing just no sensor... :-(

But, if you have a real S3 MAF from Mance, the sensor you need is going to be one he has modified with one of his o rings in it.

If you have modified a MAF yourself, (can't tell from partial part number by the way)you may be able to make your original sensor work, but it won't work well. Hard to tell what is happening without an air fuel meter too.

Problem is that as Audi evolved the MAF system they made it freer flowing and changed the mapping between sensor and bore, several times. Mance's latest MAF- the real S3- has a modified 3 wire sensor with an o- ring and a velocity stack that work together to let a lot of air into the intake system and tell the EMU (engine management unit) how much air there is.

Other sensor, housing combinations let more air in, but don't tell the EMU the truth about how much. Depening on which MMS (200 or 300) you have it can result in CEL codes or simply poor running under load- caused by lean condition. Might even cause knock sensors to kick in.

No matter who helps you, we are going to need the full 9 digit part number of your original MAF and the story of how you got to a "S3" MAF housing. Also might be handy to know what year your car is.