dess

I have a 2011 E550 with a driver only dynamic seat. If I don't turn the massager on in the first 5-7 minutes after I start the car, the dynamic seat turns off and I cannot turn it on until after I turn the car off, open the door and then restart it again. If I turn the massager on within the first 5 minutes, it works for the next 15-25 minutes, then turns off and dynamic seat stops working as well.
If I remember to turn the massager off within 15 or so minutes and then immediately turn it back on, it stays on with the dynamic seat for another 15-25 minutes. When I'm on the road for longer than 30 minutes, I'd like to have the comfort of the dynamic seat.
Could there be an air leak or a controler issue? Has anyone experienced the same issue?
Thank you

Oda112

It sounds like you might have a slow leak somewhere. Have you scanned it?

KEY08

I don’t think the massage function runs continually. My dynamic seat massage has always only run for 20 minutes or so and then shuts down. Same for 3 cars I have had with this function

dess

I have not scanned it at the dealership because it looked like it was scanned when I bought it and nothing was found. I am thinking the same thing that I may have a slow leak but not sure how to identify

dess

The massage function should turn off after 20min. but I should be able to turn it back on (which I can't until I turn the car off and restart), however the dynamic portion of the seat should stay continuously engaged to provide the side support when turning, etc.

KEY08

^ok, yes that is correct. You can turn it right back on after it shuts down and the bolsters should always be working. Sounds like a SAM issue and not communicating properly with the Dynamic seat.

dess

What does SAM issue mean and how do I look into it? Should I try to replace or reprogram something?

KEY08

The front SAM (Signal Acquisition Module) controls the functions of many devices in the car. There is another SAM in the rear that does the same. Sometimes communication is lost for various reasons and in your case the startup of the car reinitializes this communication to the seat. I have had blown seat bladders before and they do not turn off the seat when they leak. You will need to get a proper diagnosis with a diagnostic system as this issue will not be throwing a code. I think it's an intermittent communication problem.

Oda112

This actually sounds pretty plausible. Either way, a scan should reveal loss of communication, even if it's sporadic.

dess

My friend just scanned it and got a code "9ea998". He thinks it's a faulty pump that overheats. What do you guys think?

CaliBenzDriver

Fault codes definitely point towards the seat pump but many things can upset it: sensors, harness, fuse, software etc.

From that point I'd do ...:
a quick visual inspection then
run a complete test procedure of the pump
check out TSB related to this system
Reset seat codes then see which code comes back first
before considering a new air pump $$$.

Furthermore:
Codes seems to relate to 2 distinct units: Seat module + Pump module
Based on what I remotely understand...
pump may be running non-stop before "overheating" is reported...
? an air leak or pressure sensor...?
The pump itself seems functional !

What sort of mileage are you at?

dess

110k

Oda112

Looks like a leak or a kinked air line. Look for stuff that might have caused physical damage under the seat or maybe dents in the seat's back cover. I'll run a xentry simulation and see what advice it gives for this error.

PS. All the errors you have point towards a leak in the system. On all of them Xentry instructs this "check the compressed air line between M40/1 (Dynamic multicontour seat pneumatic pump) and N32/22 (Right front dynamic multicontour seat control unit) for leaktightness". There is a test Xentry can perform to check for leaks, it takes 70 seconds. Pressure loss over 70s should be less than 0.1 bar.
Let us know what you find.

dess

After years of struggling and finally accepting it not working, I had an idea yesterday that I should take apart the dynamic pump and see if there are any leaks. Low and behold, there was a leak right at the pump, where one of the connectors is plugged in. Couldn't find another (small enough) O-ring so added a spacer under the old one and for a first time ever, my dynamic seat works even after an hour (I had to go on a road trip just to test it). Hopefully this is all I needed to fix and it will not malfunction again.
Thank you all who responded and hopefully this can help others with the same issue.
Just a reminder, my dynamic seat would work perfectly for the first 20min if I used the massage function, then it would shut off and I couldn't turn it off until I turned the car off and start again. If I didn't use the massage, it would only work for 5min max.
Now everything works perfectly!
Dess