It's in the stickies...corrosion/poor connection at the sockets.

Good luck.

 

I had the same issue with a break light. The filament was loose. Vibration seemed to break the connect ion. Have someone press the brakes while tapping the brake lights. Or just replace the bulbs to see if the problem goes away.

 

Some members have also reported issues with generic bulbs and swear they had no problems after getting OE bulbs.

Virtually all of my replacements have come from autohausaz.com.

 

The lamp out message comes up from time to time on our car too even although all bulbs are good. One thing I have noticed, is that this usually seems to happen when starting the car with my foot on the brake.

If I don't have my foot on the brake, the message does not appear. Which makes sense because it is probably caused by brake lights. Voltage goes down during starting and somehow computer thinks lamp is out.

I have checked and cleaned all the contacts. They look fine, but the design is inherently bad. I thought about buying new sockets and hard wiring them as described elsewhere. But starting without foot on brake seems easiest solution

 

This may be runner up to a cheap and easy fix to chronic brake light socket problems.

Had a brake light failure. No problem, bought 2 new bulbs, showed my teenage son how to install the first one, and then let him put in the second one. While doing so, he broke off a plastic tab on the socket. Now the bulb would not light without side pressure. (Muther Fletcher!) Tried bending out the metal to develop a spring force and regain electrical continuity. No joy.

Because I did not want to drive around town with a brake light out while ordering a new socket, and I did not want my firstborn to dispair, we found that a small zip tie around the socket and metal conductor plate reestablished continuity.

Two weeks later, the opposite side brake light failed to light. Since I had just replaced this bulb, started troubleshooting by putting an outward side loading force on the socket, and the bulb lit up. Another job for a zip tie, and in 5 minutes the opposite side brake light was restored.

That was two years ago, and I won't order a new socket because it has worked just fine.

Since this repair is covered up inside the trunk, no one has to know about this cheesy repair method for a Mercedes except me, my son, and all of you.

 

In the case of the OP - frankly this irritating problem in you case "may" be also caused by a failing brake light switch. Replace with OE MB brand brake light switch only, which is good pre-emptive maintenance any way.

 

Rotate the rear bulb in its socket a few times and leave it in a slightly different position in the socket than where you found it. x2 on the above post, its corrosion.
Happened to me less than a month ago. In my case, i replaced both bulbs only to figure out it wasn't the bulb.

 

The same thing happened to me I went and replaced the socket and it works fine now.

 

How does one replace the socket? Thanks

 

Do you have a third higher brake light?

I sorted my intermittent bulb problem by taking them all out one by one and cleaning both the sockets and the bulbs.

 

I just bend the metal tabs on the socket out more and that helps