2007 Mercedes E550 4-Matic
Was driving at night, everything seemed normal until my esp light flashed 3 times then engine went in limp mode, after about 5 seconds engine completely shuts off. All dash lights still worked a/c still blowing but no engine. I coasted to the side of the road and attempted to restart vehicle and got nothing, no crank and no start, when key goes in everything seems normal car just won’t start. I got the car towed home around 11pm. Next day I got home from work and noticed battery was dead. Hooked up a charger and went to scan the abs code and scan tool would not connect, I have tried 3 different scan tools and none work ranging from $40-$300. I have checked fuses and most grounds but I am unsure what is causing the obd2 port to not connect. I’m seeing things about possible EIS (electric ignition system) and CGM (center gateway module) on forums but I’m u sure where to start.

Any advice is very appreciated.

 

The fact that:

• The ESP light flashed before failure,
  
• The engine shut down abruptly,
  
• You have no crank, no communication via OBD2, and
  
• The battery was drained by the next day
  

...strongly points to an electrical control issue, possibly involving the EIS (Electronic Ignition Switch), the CGW (Central Gateway Module), or CAN Bus network failure.

1. Check CAN Bus Network / OBD2 Connectivity

Since your scan tool can’t connect, something is preventing communication with the ECU.

• Fuse check: Re-check OBD2 port fuse, ECU fuse, and CAN gateway module fuse.
  
• OBD2 port pins: Look at Pin 6 (CAN High) and Pin 14 (CAN Low) using a multimeter. If you see no ~2.5V on both, you may have a CAN bus short or dead module pulling the network down.
  

2. Electronic Ignition Switch (EIS)

Common failure point on Mercedes. If the EIS is faulty, it can:

• Prevent the car from cranking
  
• Block communication between modules
  
• Keep the car in security/lockout mode
  
• Prevent OBD2 tools from communicating
  

Signs of EIS issues:

• Key turns but no crank
  
• No communication with modules
  
• No ESL (steering lock) noise when key is inserted (if applicable)
  

Test:

• Try another known working key (if you have one).
  
• See if steering lock engages/disengages when inserting key.
  
• Listen for relays clicking when key is inserted (if completely silent, EIS or power to it may be dead).
  

3. Check CGW (Central Gateway Module)

This module is responsible for communication between systems. If it fails or loses power, it can cut off the entire CAN communication chain.

• Typically located under the driver side dash or near the fuse box.
  
• Check for water intrusion, corrosion, loose connectors.
  
• Look for signs of burned pins, corroded connectors, or physical damage.
  

4. Battery & Power Supply

A sudden voltage drop or weak battery can cause the ESP light, CAN dropouts, and even EIS reset.

• A dying alternator or shorted battery cell may have triggered the issue.
  
• Ensure battery is fully charged and holds a charge over time.
  
• Test alternator if you get the car running again — check charging voltage.
  

5. Test with a High-End Scan Tool

If you're still getting no communication after power and CAN checks, it may be time for:

• A dealer-level diagnostic (Mercedes STAR tool or similar)
  
• A qualified indie Euro shop with experience in Mercedes electronics
  

Many generic scan tools can’t talk to Mercedes modules if the gateway is offline.

Suggested Order of Operations:

1. Charge battery fully, check with multimeter (12.6V+ engine off)
   
2. Check fuses again, especially ECU, EIS, OBD2, CGW
   
3. Visually inspect EIS – does the key respond?
   
4. Check OBD2 port voltage, see if CAN signals are alive (~2.5V)
   
5. Inspect CGW for water or connector damage
   
6. If all fails, consider professional diagnostic with STAR system
   

Tools That Can Help:

• Multimeter (to check fuses, voltage at OBD2)
  
• Power probe (to inject/test power on circuits)
  
• CAN Bus tester (optional)
  
• A scan tool capable of reading Mercedes modules (iCarsoft MB II, Autel MS906, or STAR

I used Ai to help. speed up the process of explaining. Good Luck.

 

Ok, think back over last couple weeks

What events or little symptoms might have popped up, even briefly.

Anything out of ordinary.

Lights flashing, things not working on first try. Funny noises, anything at all out of ordinary? Any weirdness when key turned on or off?

Do you have a 2nd key?

How old is the battery?