Yea, I deal with a lot of BMW's and VW's that use Bosch OE MAF's. Have also run into a LOT of situations where Asian counterfeit MAF's have been purchased for much lower prices. Seems these MAF's lack the Platinum hot wire and many of the cheap MAF's end up using thermistors that many times look like the MAF values are fine at idle, but do no measure correctly at higher cruising speeds.
I tell EVERYONE when the change a MAF for ANY reason, keep the old one as it may end up back on the car in short order.
Many of the counterfeits are very hard to determine from the OE sensors. You must purchase from a reliable source and even then you may get had. All the markings and labels are good copies.
You have to LOOK very closely to determine if you think you ended up with a counterfeit and just because it was more expensive or came from a reliable source is not guarantee anymore.
This is getting to be a big problem and counterfeit MAF's have a lot of margin due the fact the good ones have Platinum and are so expensive.
Why counterfeit $3-$5 spark plugs when you can counterfeit a $300 MAF that is mostly injected plastic and costs you maybe $5 and you can get $150-$200 for it!!!
Watch out, might be even more junk showing up now that 3D laser copiers and 3D printers are getting so good and cheap.
A few hours with a 3D copier and printer, you have a exact copy or you have the dimensions scanned in for cheap replicating.
3D printing will be a great thing, right now people may be using it to scam, but in short order you and I could use them to build our own parts. But with better quality than the OEM.
I know if I could replace most of the pieces and parts that make up my bug with higher quality I would do it. I could keep this bug going forever if I had the ability to 3D print out many of the parts.