Hi all. we have a 2013 Mercedes GL550. After a 3 hour drive and then leaving the car for a week we came back to a malfunction warning in yellow on the dash for the suspension. I tried to raise the car then lower but it got stuck in the highest position in the rear. I had a mechanic scan the code and we got a C156E-00 code, he tried to recalibrate the suspension but it wont work and rear wont go down. I have checked the fuses and he checked the wiring connections. We have also randomly got a warning for the adaptive headlight inoperable.

The mechanic feels it is the valve block but the code seems a little vague.

I have read and read but cannot find this same issue. I have tried the sport and comfort buttons but nothing moves the suspension now and maybe that is because the warning is constantly on.

Does anyone have input here? Thank you in advance.

 

2014 owner of the same here. I’ve not heard of that code so we’re in the dark a bit here, so a couple of suggestions if you don’t have access to the MB scanning software Xentry & immediate drive ability desired:
- reach out to folks in your area to see if anyone has Xentry diagnostic s/w on OBDI scanner tool - if so look up this code & learn all the particulars as to what causes it. Conversely, go to local MB dealer and ask for service manager for printout of this code’s effects. You need more information so you’re not chasing your tail and throwing money at parts.
- if a no go, locate fuse diagram for vehicle. Remove the air pump control relay, inspect visually connection terminals for discoloring and smell it - any strange burnt smell? These are relatively inexpensive - replace it. Solve problem?
- remove connector at air pump under front passenger wheel well area. Clean both connections well with contact cleaner solution. Inspect, anything?
- valve block can go bad but they are made fairly well. Assuming your mechanic is an indy- they have Xentry or no? Assuming no based off of knowledge gap. Have they replaced a valve block before & know operational procedure for R&R? - a little weariness here tbh.
Results?

 

As for headlight inoperability, I have had same issues and found that by manually swiveling back & forth the internal assy (assuming you have the tracking headlights that move left to right as steering wheel turns the same) this solves the problem. Access is gained by removing inner fender well, removing headlamp assy plug, put fingers on swivel assy and rotate full left to right & vice versa. Makes a sound similar to a remote control car steering motor, be gentle, but compare L & R sides. Should have same amount of physical rotational movement- if no something not right. Go from there.