I was getting the dreaded Passenger SRS fault message on startup in my '14 E350 wagon, and the airbag light on the dash was on. Interestingly, the Passenger Airbag on/off indicator was working correctly, so I figured it was NOT the seat occupancy sensor. Ordered an iCarsoft code reader from Amazon. Turned out to be a code for the Seat Position Sensor - open circuit. Hmmm. Very little luck on that searching in the forum and a general Google search. Could not even find a part number for it, though I did find one on Alibaba so I had a hazy idea of what it looks like.

Got some decent weather today, so figured I would have a poke around. Jacked the seat up as far as it would go and wedged myself into the rear footwell to have a look. Hey - it's right there! And huh, there is a blue connector that sure looks like it ought to have something plugged into it. rummaged around to no avail under the seat, but then happened to spot a stray cable with a blue connector between the side of the seat and the car when looking from above. Plugged it in and voila! Problem solved. I suspect that the seat occupancy sensor was replaced at some point given that things were not attached quite right under the seat as far as cable anchors, and the dealer monkey who did it likely broke the latch on this connector. So it just slips in and out now. A small ziptie has made it much more permanent.

This car's ENTIRE service history until a couple months ago was at the dealer in West Palm Florida. Sigh. I see that Mercedes dealers are no better at doing this stuff right the first time than the BMW dealers I have been dealing with for decades. Always something not right every time they touch one of my cars. Though I do seem to have my BMW dealer trained that I am a fussy SOB and WILL bring the car right back if anything is amiss, and I WILL be checking up on any warranty/recall work they have done. Took a few years. But as usual, if you want something done right, best do it yourself if possible!

Kevin Rhodes
Port Charlotte, FL / Westbrook, ME
2014 E350 wagon 70K

 

I am in the same boat, don't have to drive at all with the new position. Now I get little more time to fool around cars.

 

The same happened to me once picked up my mom several years ago. She opens the rear door passenger, gets in the car and when I shifted to move I get the Passenger SRS message. It puzzled me for a moment, but I kept going while thinking about it. When reaching our destination, I asked: "Mom, did you notice something off when you got in the car?" and she replied that she may have stepped on something under the seat but could not see it in the dark.

I stayed, took the flashlight (always in the left rear trunk compartment ), and did exactly as you did: moved the seat all the way forward, and there it was: a blue connector dangling on its own. Found the empty slot where is fitted, and voila the message was gone.

I can only assume I may have moved it out of position closer to where a passenger could inadvertently touch it when vacuuming the rear of the car (w/o disconnecting it). I am a bit more careful when vacuuming (though not certain that was the source)> It has not happened again.

 

It's nice to see you found the glitches and shared with us
My stupid bimmer needed to have that module replaced , but thankfully warranty helped me out

 

When I first bought my pre-owed E400 and took it for full Xentry scan as pre-purchase simple inspection at a reputable dealer, the rear parking sensors ALL of them showed error.
I accepted car as is.

Guess what actually happened ?
Probably MB Indonesia, they did not click well the primary wiring harness connector of those sensors at the rear bumper.
It was simply a disconnected connector. I think it is because the First-Aid-Kit is stashed there and that connector got pushed around when one inserted the First-Aid Kit into the cavity.
Right side at trunk, rear of REAR SAM Fuse Box.


This one



Some tip.......
I do not know if this is because of my country high 80-90% ish humidity all year round or junk quality, those grey foam MB uses to stop cable or connector rubbing noise, on mine by year 7th they turn to dust when I squeeze them.

On the interior roof liner, at the overhead light, same thing happened, foam becomes dust.
Overtime, loosing the foam aka wire becomes loose and free to vibrate to touch other things vibrating, can produce very minor irritating sound at certain speed or frequency.
It is a low level sound, but irritating nevertheless.

Once most of the foam becomes dust at many enough wires in car interior, then the car will have the stupid minor noises at certain speed/frequency.
I am hyper sensitive to these kind of noises.


Someday I need to open up my roof liner again !!!! Damn. 1st time was panaromic main bolts re-tightening and loctite thread locker treatment for the dreaded CLUNK sound pano is famous for when car is "twisted".

Here is what will generate the noise I mentioned. Below is the reading light + switch assy at the roof liner/review mirror.







These grey foam will become dust.

 

I don't think the foam turning to dust is a high humidity problem. My two MBs live in the arid southern middle west of America, and I notice the foam turning to dust as well (on the older car). It may have more to do with heat -- hotter climates -- but I'm thinking that the foam simply has a life where it is soft and pliable, then with age turns stiff and brittle. Amazing how it turns to dust when you squeeze it.

And I'm guessing it's not just a Mercedes problem...

 

Your "older car" is more than 10 years or less ?

 

It's a 21 year-old C320 (M/Y 2001) I replaced the headliner 8 years ago, because its adhesive foam layer turned to dust 8 years ago, and the headliner fell.

Tip to all: Do NOT use your thumb to push into the headliner... for any year MB. Looksie, but no touchie! Do NOT use pressure when vacuuming the headliner, either!