amazer98

So I bought my first MB a month ago-- a 2008 C300 4mat Sport and love it... but a problem has materialized, seemingly out of thin air. The other day I got a warning message on the dash display:

FRONT LEFT SEAT SRS MALFUNCTION - See Dealer for Service

This message appears shortly after start-up and, at the same time, the red AIR BAG icon appears on the dash. After maybe 10-15 seconds, the message and icon disappear, though sometimes they re-appear later during the drive.

Not sure what to make of this-- is the problem seatbelt-related or airbag related? Maybe there's a sensor in the seatbelt mechanism that's not working correctly?

Is this a serious issue? I certainly don't want to go to the dealer and be charged $600 or $1000 or whatever crazy amount MB feels it can impose for a problem like this.

Sportstick

Is it serious? SRS is "Supplemental Restraint System", which means the air bag is involved and may not deploy, but the seat belt is considered "primary". We can't guess as to the location of the problem, but the result is potentially life or death. Go to the dealer.

rb23lb

ah ha!

I had this same exact problem and message...

took it into the dealer last week, the replaced the drivers seat belt buckle under warranty... I have an '08 as well...

looks like the seat belt buckles locking mechanism wears out after a while and triggers the sensor...

you have the exact same error message and issue I had, I can get you the part number replaced when I go home tonight and check my invoice...

RLE

The seat belt buckle problem has been going on for more than ten years at Mercedes. Porsche and Audi have had the same problem so you have to wonder why they haven't forced the manufacturer to improve his product.

When the SRS light is on, the system if OFF so get it into the dealer. My C300 hasn't had this particular failure but my '01 C320 had three buckle replacements early in it's life.

amazer98

Thanks for the feedback, guys. Since my car is out of warranty, any idea what the fix would (should) be?

Also, how can a buckle wear out? -- it's a hunk of heavy duty metal after all. Or probably you mean the mechanism that it clips into... could that be it?

Anyway, it hopefully won't be too expensive to repair.

Sportstick

The car may be out of warranty, so think of it as preventive maintenance.....for you!!.

RLE

That's not it.

Each buckle contains electrical contacts which tell the SRS controller who doesn't have their belts on. An unbelted occupied seat causes the airbags to deploy at lower speeds and G-forces.

Once again, in my unlamented W203, the driver's buckle was replaced twice and the other front buckle once.

rb23lb

ya I meant that from locking and unlocking so many times, the mechanical action causes something to wear out...

which is the electrical contacts, after reading your post . thanks

acr2001

I had this same problem in my piece of junk W203. God I hated that car, nothing but problem after problem.

theramman

HA!! Looks like it's still going on for the 09 model's as well. Just purchased my first MB, 09 C350 4Matic (Im in Canada) and Ive already had to take it in for the exact same problem.

LandSeaAir

My dad had an 03 S-class with tons of lights on, SRS, Pre-Safe malfunction etc. and when he finally totaled it, everything deployed as it should of. I guess it always ends up being a minor issue that triggers it.

tivoboy

I just had the same thing start happening this past week. Actually, only happens with the GF drives the car. under warranty, I'll take it in (but only have one car now since somebody just wrecked my jeep last weekend! so that will be a pain)

huy801

I had the same ting on my 08 a couple months back and I ordered a new buckle from (http://www.mbzwholesaleparts.com/) they are an actual dealership that does online sales and their prices are really good. It is very simple to replace, but you need Torx sockets and drivers, I dont remember the sizes but I just bought the whole Torx set @ Harbor Freight for like 15.00 or something. You move your seat all the way forward to remove the two bolts on the rail, then move your seat all the way backwards and remove the two bolts on the rail. Now you manually pull the seat forward about 5-6 inches then tip the seat onto the rear seats. Now you can access the wiring harness. The connector for the seat belt is yellow and has two pins on the inside, I believe it is the middle connector in the harness array, it is a PITA to deal with. Once that is done snip a couple zip ties and then jump in the back seat from the passenger's side and unbolt the seat belt buckle. Now reverse everything you did and get it back together. The light will still be on, so you need to find a buddy with an OBDii scanner/Star and reset the code. Now you are all done.

chuang

Do you have more information about this? I meant did the dealer just replaced the seat belt plastic buckle, or does the buckle actually has some sensors in them? Can these sensors sometimes overly sensitive, and when that happen would the car computer record something for the mechanics to diagnose (so that they know it's the buckle that need to be replaced)?? Thanks!

chuang

Thanks for all these info. This is very helpful. It seems that the problem still exist in 2012 C class (at least happened to ours). Just curious, when car battery is low could it also trigger this SRS malfunction message? How can you "confirm" that it's the buckle that is faulty?? From this picture I can't see there is any electric sensors on the buckle?? Thanks!

acr2001

Low battery could potentially trigger an SRS malfunction.
You can confirm it is the buckle by reading the code (mechanic with code reader or dealer)
The wire leading from the seatbelt buckle is clearly visible in that picture. The actual sensor is inside.

Also, when the SRS light is on, the entire SRS system and all airbags are non-functional.

cxesar

what kind of obd2 scanner u used?

huy801

Brand of OBDII scanner does not matter, just stop off @ the local checker/krugger/autozone and borrow their scanner to read/reset the code right there in their parking lot.

RLE

Also, SRS warning light cannot be extinguished by a restart. It usually takes the dealer laptop to do so. Whether a generic scanner can do it would be good info so don't forget to post your results with it here.

huy801

Not true, the generic one I borrowed from Checker allowed me to reset the code.

RLE

So the buckle assembly has been replaced or was it a low battery?

huy801

Yes, get a replacement, then reset thecode.

cxesar

ran into the same problem!!...very annoying srs message pops up on dash as soon as i start the car...the passenger airbag light flickers when no one is seating on the passanger seat so i came to the conclusion the cushion sensor is going bad triggering the faulty code...im not gonna buy a new seat for some outrageous price instead went to ebay and got an emulator ($25) that tricks the sensor that the seat is occupied at all times cant go wrong with that..at the same time the seat belt light doesnt light up anymore when i dont wear my seatbelt making me think the buckles are goin out too...anyways those are 45 and easy to replace...now the hard part is to reset the code with the star diagnostic tool i guess ill have to bring it in to a shop to get that done!...

politixian

Anyone know how much this will cost me? The passenger side SRS just went off and my car went out of warranty about two months ago.

How much will this fix cost me more or less if I send it to the dealer?

Jonathantripp

My buddy at a mechanic shop let me use his, a Matco brand scanner and it allowed me to reset the airbag light, my srs light came in from unplugging the connectors... Thanks every1 this thread was very informational