Although the MAF sensor seems to be more problematic in the W210 I thought this might have some application to all the rest as well for a couple of reasons. First, the potential supplier here claims that his part will fit "almost every model Mercedes from 1998 till present" and second, we're always willing to save significant dough if it won't hurt our cars, right?
At any rate, if you've had the joy of having to replace a MAF sensor, then you know that it's a fairly expensive fix (few hundred to several hundred depending on how much your garage wants to soak you and where you source the part if you're a DIY-er). Someone in the 210 forum posted a link to an e-bay ad (since they end all the time I won't bother with a link, but if you search e-bay with the phrase "Sensor Mass Air Flow Fuel Trim" you'll find the item). What the seller is actually offering is the insert for the MAF assembly and the sales price is right at $100, which seems at first blush like a great price. I've copied the picture fo the item and added it to this post so you can see what s/he's selling.
I'll admit I was very
curious, so I sent the seller a question asking if he'd provide the Bosch part number so I could verify it was really a Bosch part, etc. His reply was a mere "no" -- literally, nothing more, nothing less -- which served only to increase my sense of distrust/concern. While he generally has excellent feedback, I was still concerned. Too, once feedback is posted, if there are problems down the line you'd never, ever know. Now I don't know the seller or his/her motives, etc., so you can draw your own conclusions. I just thought this was all worth hashing out a little bit so we can avoid a potential ripoff.
So, today I called Bosch US and spoke directly with one of their representatives. They advise as follows: The insert for the MAF sensor is absolutely not sold separately by Bosch in the US. Further, to the Bosch US guy's knowledge, it is not separately available anywhere on the globe, but he can't speak for sure about Europe, Asia, etc. Those inserts are properly destined and intended for the manufacturers of the MAF sensors. The specific reason that they don't offer them separately is that while the insert can indeed be installed in many different MAF assemblies, once installed it must be calibrated and tuned for the specific application and assembly. Neither Bosch, nor other MAF sensor manufacturers, nor vehicle manufacturers, recommend or support the simple replacement of the sensor insert. That certainly makes sense and sounds reasonable to me -- and it would also help explain why the e-bay seller can note that it "fits" so many different models.
That said, I'm confident that simply installing just the insert will permit the CEL to be cleared, but the remaining question -- as noted by the Bosch rep -- is whether it will actually provide the range of feedback and operability that Mercedes intended for any particular application since the insert is not calibrated and tuned as part of an assembly. It does seem contrary to reason that a single insert could be correct for everything from the little 2.3L four to the smooth 4.3L V8.
Okay, then with that as a backdrop, a couple of things emerge. First, if you're in the market for a MAF sensor, you might consider a couple of things. One, how often are you going to have to change it? If you've gone 60 or 80 thousand miles, then even if your dealer seriously
rips you off you're saving less than a penny a mile (maybe a dollar every 130 miles or so). Is that a great benefit when you may end up with worse fuel mileage (which will surely cost more than a penny a mile), an inability to pass a strict smog test or, worst case scenario, you end up damaging one or more other sensors because of the imbalance caused by an uncalibrated MAF sensor?
Second, we know MBZ vehicles are very technologically advanced, so isn't that reason enough to purchase the correct MAF assembly for our specific vehicle?
On the other hand, if you need a MAF sensor and have either purchased this insert or would like to be a guinea pig for the rest of us, please complete the transaction and post up regularly for a while and let us know the results of the experiment. If in fact it works fine for an extended time, then there is no reason for the rest of us to pay out extra money (and dump extra trash into our landfills).
I think I've bored you enough, so that's it.
As always, take care and enjoy the ride!