Since I am back on the forums asking for assistance with my climate control light bulbs, I figure I should go ahead and share a recent story.

Last summer, after getting my SLK230 out of storage for the season, I had the doom and gloom of the check engine light to come on, the code was for the MAF sensor. I searched around on the internet for options and came across a chinese company, called Henko, offering aftermarket sensors. On their contact page they indicated that a potential customer could request a "sample". Even though they were looking for a US distributor and a business to business relationship, I went ahead and replied via email and requested a sample. Without many questions, they were extremely quick to offer and ship a sample.

I thought, SCORE!!! a free sensor that would cost me upwards of $350 from Bosch and even more through Benz (same Bosch sensor in a Benz parts box). I installed my score in the car and things seemed to start out rough but OK. Since I didn't have a Star Diagnostics computer to reset the system, I knew that things should run a little rough until the computer had enough new data from the sensor to adjust and learn.

For the next 200 miles, the car ran rough, ran rich (as I could smell unburnt fuel in the exhaust), stuttered, stammered, missed and generally had diminished performance. Then started the worse issue, under hard accelleration, around 4500RPM, the car would fall flat on its face, stutter and then run smooth but absolutely NO accelleration without a written request, two days in advance, to the horsepower gods. Come to find out, my supercharger is the series that has an electromagnetic clutch, kinda like an AC compressor, and the computer was turning the supercharger off. The SLK 4 cylinder running normally aspirated is a lackluster driving experience and the term "gutless wonder" was coming to mind as Geo Metros and the like could smoke me from the light.

I took it to a local shop that specializes in Benz as the owner is a former Benz Master Tech and dealership service manager. Since the MAF sensor was the most recent failure, we of course went straight to it. The signals from it were showing well and spec'ed out as proper... We then went to the air bypass valve as a possible culprit. A used air bypass valve, 2 weeks in the shop and $500 later the car was no closer to running correctly or consistantly.

I chased this problem all last summer and tried fuel system cleaners, new plugs, etc just dumping good money after bad. By the end of summer I was frustrated and ready to drive it to the crusher. Instead I put it back in storage and forgot about it for a awhile.

This summer when I got it out of storage, I was immediately greeted with the poor performance. I had a nagging feeling about the MAF sensor and decided to nut up the $350 for a Bosch unit, even after multiple passed tests of the Henko unit and it's signals, I could come up with no other answer. It was $350 or get rid of the car, I was that frustrated.

Upon installing hte Bosch sensor, IMMEDIATELY the car returned to its previous performance and manners.

Overall, my "FREE" sensor cost me a summer of fun and about $750 in chasing a phantom problem.

That was first and last experience with aftermarket sensors for Mercedes Benz. Someone once said, "The bitterness of poor quality lingers long after the sweetness of low price is gone."

I hope my story of woe will help keep others from making the same mistake I did.

 

Yup, seen that type of story on many, many forums...

I even got bitten... once

Bazzle

 

At least yours was free, there are plenty of people that got bad counterfeit MAF's on ebay silkscreened with the right part number and logos.

 

So the ones on ebay are not a good bet? I see them for 90 dollars on there? Is it the chineese brand that has been rebaged?

 

Here's my non-genuine MAF replacement, of unknown origin (a local indy mechanic/friend sourced it from somewhere):



The funny thing is that with this part installed, my car (a 320) ran just fine, the only problem was the CEL always being tripped with codes P0170 and P0173 (fuel mixture adaptation beyond limits, banks 1 and 2), just like with the original sensor. Eventually, I had the car into a local MB dealer for some warranty work and had them troubleshoot it. They put in a genuine Bosch MAF, and whadya know, no more CEL.

 

I've heard of lots of people being taken on ebay on MB mafs but I never heard of someone being successful. Only buy from reputable parts stores or the dealer, not off ebay.

 

Similar story here. I went into the shop for a/c problems and came out with a bad main ecm, bad traction control module and busted supercharger. At least that is what the MB dealer told me. After letting my SLK 230 sit in the garage for 3 years I started researching these issues and like others found out my K40 relay was junk. I replaced it with a new one. The assorted dash lights finally went out but the car still would spit and sputter like it had bad gasoline. After more reading I took my MAF out and cleaned it good, using proper MAF cleaner. She now runs like a brand new car. Thankfully I didn't give the dealership $3k+ for no reason. Keep up the good posts.

 

Similar story here. I went into the shop for a/c problems and came out with a bad main ecm, bad traction control module and busted supercharger. At least that is what the MB dealer told me. After letting my SLK 230 sit in the garage for 3 years I started researching these issues and like others found out my K40 relay was junk. I replaced it with a new one. The assorted dash lights finally went out but the car still would spit and sputter like it had bad gasoline. After more reading I took my MAF out and cleaned it good, using proper MAF cleaner. She now runs like a brand new car. Thankfully I didn't give the dealership $3k+ for no reason. Keep up the good posts.

 

Just wanted to say thank you to everyone for this discussion. I'm not even going to look at ebay now.....headed directly to Arizona Autohauz!

 

I had a similar problem also. The fake MAF lasted me about a week before taking it out. Ended up having to buy the OEM one anyways

 

Similar problem happened to me on my CLK320 98(I have too a SLK230 98 with no problem): rough iddle, bad acceleration.

I change the MAF for a Pierburg instead of Bosch (the "maf-shop.com dealer in deutchland says it's stronger), plug it and ok, just a little problem, little lack of power.
So I reset the ECU by unplugging negative side of battery 2 minutes and... car undrivable!!! no power at all, very very rough iddle;
I order 2 cheap ebay MAF, no way, they don't work.
I order an OEM BOSCH MAF and... perfect, better than ever !!!!

I was very afraid the ECU was dead: codes were indicating misfiring on all cylinders bank 2, lambda and maf problem...

Conclusion: in the future, only OEM BOSCH MAF for me.

For europeans, it's quite cheap in maf-shop.com, about 200€ for OEM quality; in France Mannespièces quite cheap too. In Reunion Island, in Indian Ocean where I live, it's far more than 1000$ at MB shop!

 

PEOPLE DONT SPEND THE MONEY ON A NEW MAF BEFORE USING A MAF CLEANER FIRST! My 320 had its CEL come on and was barely running, took out the MAF, cleaned it with specific MAF cleaner and it runs like a charm, the light went out in no time. You have nothing to loose trying to clean it first, secondly if you can pick up a genuine MAF for cheap at a junkyard, clean it and have it as a back up.

PS sorry for the caps, I know some forums hate it.

 

The bitterness of poor quality lingers long after the sweetness of low price is gone.

We can't agree any more. Often it's the bad supplier who made a bad effect on the market.

 

I bought a maf off eBay for £35 and have no problems at all. It took around 30 mile for the ecu to adjust to it and the car runs really smooth with much more power, and is better on fuel consumption. I only buy off eBay from people in uk and always read the feedback first