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My S4 has just been diagnosed with its 2nd MAF sensor failure this year. The original problem was diagnosed by AMD and repaired under Audi extended warranty by Whites, Camberley. It was definitely quicker with the new part. Recently my car has been feeling a little off colour. No quicker than a Honda Civic Type R I followed recently and a disappointing amount slower than an S4 4.2. I have also noticed some surging on light throttle opening, but generally it drives OK, albeit a little slow.

I asked Whites to have a look for a boost leak whilst MOTing it today. I must say that one of the hoses (the fat one) going into my left DV had some surface cracks where it bends which looked a bit suspect. Whites have just told me it needs another MAF sensor. This will be swopped later this week under warranty.

Now should I be worried about 2 MAF failures so close together? What nasty underlying problem could be causing my MAF sensor to become contaminated? Oil contamination? Where from….?

David

David,

Normally I would expect contamination which would imply that your air filter is not protecting the MAF sensor as it should.

However based on what I have read on this site (i.e. I have faith that it is true but don't know that it is), the S4 was delivered with either a Bosch MAF or a Hitachi MAF, depending on when it was built. Apparently the Bosch MAF has proved to be more problematic than the Hitachi. So if you have a Bosch MAF, then maybe your 2 failures are just down to bad luck rather than a common cause.

Thanks Dave,

I will try to find out what I have now and what they replace it with.

David

David,

The Hitachi and Bosch are not interchangeable without re-wiring the connector.

Could you give us some more info like year/model of car (if known). The Bosch part is widely thought to be "less" reliable than the Hitachi unit. Also mileage covered could be relevant. If you habve a Bosch unit then they are widely accepted to be less reliable on the Audi forums. However the fact Audi swapped to Hitachi part must tell any owner with any common sense that there is something amiss. Car manufacturers don't swap manufacturers lightly. Especially when it means changing wiring looms etc...