Here is a helpful analysis on SRS light/ Airbag warning message on Mercedes Benz vehicles, from reason to solution.
Why does SRS light/ Airbag warning message to appear on Mercedes Benz?
-seat occupancy sensor in passenger seat;
-low voltage in the car electrical system. Battery dying.
-seat belt latch;
-steering wheel clock spring;
-seat belt sensor;
-damaged wire contacts at the doors;
-defective, damaged or loose contact at the impact sensors
How to read and reset SRS/ Airbag light?
Very often the SRS/Airbag light goes on mainly because of a dying battery. But, if the light is on, it will stay on when you install a new battery, until you manually reset it.
That is, 2 steps to solve SRS/Airbag light on.
Install a new battery;
Reset SRS/ Airbag light.
Instruction on How to Reset the SRS Light on a Mercedes Benz:
1. Locate the fuse panel cover and remove it. This is located on the lower left side of the control panel on the driver’s side of the car. Find the port that fits the OBD cable and plug the scan tool’s cable into this port.
2. Put the key into the ignition and turn it to the “Run” position. This is the position just before the engine starts. Look at your OBD scan tool and write down the codes it displays.
3. Check your owner’s manual for what the codes mean.
4. Unplug the scan tool and put the fuse panel cover back in place. Take your vehicle to your local Mercedes dealer to have repairs made, if needed.
5. Repeat step 1 (locate the fuse panel….) when you return home. Put the key into the ignition and turn it to the “Run” position. Wait until the SRS light turns off. Remove the cable and put the fuse panel cover back in place.
Optional tools to reset the light:
Airbag/ABS SRS light service reset tool MaxiCheck
(DS708 is will be a better choice if money is not an issue for you and you have many cars, for DS708 covers more vehicle and can read codes or diagnose on more systems in the car.)
Cheapest & users’ recommendation:
MB Carsoft7.4 Multiplexer
My experiences: A copy (thanks gurunutkins) of CarSoft V7.4S scanner. The Mercedes Multiplexer. My wimpy old desktop PC used with a 25-foot serial extension cord addition. On my W203 C class 2002 C230 Kompressor Coupe, Manual 6 speed, Audio 20 HU, CDC (added – read later, no other Audio or phone Fiber optics installed), with the basic HVAC control head. And a SRS light on the dash & MFD.
Short Summary: Great experience. I scanned thru my OBDII port and found all errors. I reset my SRS fault light that I know I caused when I blew Audio20 HU fuse #64 and ran the car during my DIY MB OEM CDC installation like 3 weeks ago. It triggered many Comm. errors in many systems-arrghh. I am now left with a DCM FL and DCM FR error, but they are not tripping any light or malfunctions indications to dash. I also am super pleased that I WAS able to code my used DIY MB OEM glove box installation CDC, to the Fiber Ring, and now that specific DB2 scan is 100% error free.