How do I restart SOS in a Mercedes Benz?
You cannot simply restart the SOS on an older Mercedes. If your car shows "SOS TeleAID service is not Activated" or "SOS defective Please Visit Workshop", it has the old analog TeleAid system, which stopped working when the analog cellular network shut down around February 2008. You have two fixes: disable TeleAid with the Mercedes Star Diagnostic tool, or have a Mercedes dealer switch the car to the newer mbrace SOS system (or convert the analog unit to a digital TeleAid unit).
On newer cars the Mercedes-Benz SOS / Emergency Call service connects you to an Emergency Response Specialist at the Mercedes-Benz Emergency Response Center when you push the SOS button, and sends the car's location and identity in a separate data transmission so help reaches you faster.
TL;DR
- Cause: TeleAid in Mercedes cars built before 2008 used analog cellular data, which went away around February 2008.
- Warning text: "SOS TeleAID service is not Activated" or "SOS defective Please Visit Workshop".
- Fix 1: disable TeleAid with the Star Diagnostic tool (Xentry software on a 64-bit Windows 10 Professional PC with 4 GB of RAM or more).
- Fix 2 (recommended): ask a Mercedes dealer to switch the car to mbrace, or convert to a digital TeleAid unit.
- mbrace SOS works with the ignition on or off, for up to 4 days after the engine last ran.
- If this is not your case, read the Mercedes me app and QR code guide.
Table of Content
- Why does my Mercedes show an SOS warning?
- How do I fix the TeleAid SOS warning?
- Is TeleAid service still available?
- What do the TeleAid SOS buttons do?
- What is the Star Diagnostic tool?
- Which option should I choose?
Why Does My Mercedes Show An SOS Warning?
TeleAid was fitted to almost all Mercedes Benz vehicles built before 2008. Those cars now show a message in the instrument cluster: "SOS TeleAID service is not Activated" or "SOS defective Please Visit Workshop".
Both messages have the same cause: TeleAid is no longer supported because it uses the old analog cellular data transmission, which went away around February 2008. Mercedes vehicles built after 2008 were fitted with the Mercedes mbrace system, which uses newer data transmission.
| System | Cars | Network | Status |
|---|---|---|---|
| TeleAid (analog) | Built before 2008 | Analog cellular | Not supported since around February 2008; shows the SOS warning |
| TeleAid (digital unit) | Converted older cars | Digital cellular | Works after conversion, at your own cost |
| mbrace SOS / Emergency Call | Built after 2008 | Cellular plus GPS | Works with ignition on or off, up to 4 days (96 hours) after the last engine activity |
How Do I Fix The TeleAid SOS Warning?
There are two options:
Use the Star Diagnostic tool: The first option is to disable the TeleAid system with the Star Diagnostic tool, which you can buy from Amazon or from a car workshop. Make sure you buy a genuine one. The tool is explained in the Star Diagnostic tool section below.
You can also do the job by installing the Mercedes Benz Star Diagnostic software (Xentry) on your computer, as below. First make sure the computer has enough free storage, at least 4 GB of RAM, and Windows 10 Professional (64 bit) or later.
- Get the Xentry installation file and decompress it.
- Run the file as Administrator and follow the recommended installation steps, choosing your language.
- Confirm the destination folder for the Xentry files and let the installation run.
- When the installation finishes, click 'Finish', restart the computer and run the software.
- The software asks which hardware you use: 'Diagnosis VCI' or 'SD Connect'.
- Click Next until you reach the 'Star Key' menu, where the software picks the latest Star Key for you.
- Choose the car brand you want to diagnose.
- Choose the model of that brand.
- Note: along the way you will also see the IP address settings. There you can connect to C4, or to C6, but C6 needs a proper VCI to register and a USB or Wi-Fi connection to the computer.
These diagnostic tools, hardware or software, can reach many control units, including:
- ECU
- Sensor Actuation
- ABS
- Air Bags
- Keyless entry
- Engine Immobilizer
- And 45+ other control units.
For reading generic fault codes without Star Diagnostic, see the OBD2 troubleshooting guide.
Switch to the mbrace system: The second option is to switch the SOS system from TeleAid to mbrace, which is newer and has newer safety features. You will need to visit a Mercedes authorized service center for this.
mbrace also lets you control some of the car's functions from your smartphone, through the Mercedes app. Today these services run through the Mercedes-Benz app; Mercedes says activation can take up to 48 hours depending on the coverage zone. If remote functions in the app stop working, read the Mercedes me remote start troubleshooting guide.
Is TeleAid Service Still Available?
Yes, you can still use TeleAid, but you need to convert the analog unit to a digital TeleAid unit.
This is done at your own cost, and you are unlikely to get a digital TeleAid unit from an authorized Mercedes Benz dealer, because Mercedes dealers will most likely change your analog TeleAid unit to the latest mbrace SOS system. Contact your Mercedes dealer for details.
What Do The TeleAid SOS Buttons Do?
The buttons in a Mercedes TeleAid SOS system and their uses:
- Wrench Button: for roadside assistance with the vehicle. It sits just below the "i" button.
- "i" Button: for information about the TeleAid SOS system. It acts as a 'help' button when the driver needs something explained.
- SOS Button: for real emergencies, when the passengers or the driver need emergency help. Mercedes asks owners to use the Wrench or i-Button instead for non-life-threatening problems such as a flat tire.
What Is The Star Diagnostic Tool?
Star Diagnostic is a tool for troubleshooting the software and coding in the control units of your Mercedes Benz. It can also read or delete a faulty program or code.
You can buy the Star Diagnostic tool from an official or authorized Mercedes Benz dealer or from independent workshops. It is also available from STAR TECHinfo, the official Mercedes site for special tools and software.
Which Option Should I Choose?
The SOS warning comes from the TeleAid system, which no longer works now that the analog cellular network is gone. I recommend option 2, switching to mbrace, because you don't have to reconfigure the car's systems yourself. Your owner's manual shows which emergency call system your car has.
If you go with option 1, configure the car with the Star Diagnostic tool under the guidance of a Mercedes professional, because the tool is sensitive, expensive and needs expert knowledge.