I have read through most of the older threads on "starter issues" and my issues appear to be different from most. Approximately two weeks ago while my wife was on a shopping trip the car refused to start after making several stops. Everything worked fine for the first 4 stop/start actions but after on the 5th stop it would not start. Key in the ignition, all instrumentation lights fine, key turned to start, and engine turns over two times and then nothing. Repeated start procedure numerous times with same results. At that point I was called to rescue her and while I was on the way to her location, approximately 20 minutes later, she made one last attempt to start and ......voila......everything worked properly, and engine fired on the first try. Over the next several days the vehicle was driven for 7 short trips totaling less than 10 miles. The vehicle started fine 11 times but, on the 12th, try the starting problem showed up again. This time, however, repeated attempts over several hours to start were unsuccessful. At one point I even tried to jump start the vehicle thinking the battery might be getting low. The next day. after while waiting for a tow to the MB Dealership, I decided to try one more time to start the vehicle and, lo and behold, it started fine. Realizing this was going to be a continuing problem the vehicle was still towed to the MB Dealership for service.

The first diagnosis of this problem once the dealer had inspected everything was that it was a battery issue. The battery was indeed four years old, and its time was indeed running out, but it had never shown signs of failing. Nevertheless, I authorized them to replace the battery but advised them to keep looking for the real problem. The battery was replaced and at my insistence I recommended they test drive the vehicle for 5 - 10 miles with several stops and starts along the way. On about the 4th or 5th stop the vehicle refused to start! Surprise, surprise! Since then, they have been unable to duplicate this problem in the shop. The only readings they are able to get indicate the problem could be either part of the anti-theft system or something to do with the vehicle being towed. I have my doubts about it being a tow issue since the vehicle was actually driven onto the flatbed tow truck under its own power.

Others with similar issues have mentioned the problem could be connected to the Immobilizer circuit, the DAS unit, the crankshaft position sensor, a fuel relay switch or even the starter motor. Two years ago the K40 relay unit was replaced by another MB Dealer after experiencing a shut down while driving. Fuel does not seem to be the problem, since the vehicle runs fine once it decides to start. The fuel pump was also replaced 3 years ago. Anybody got any suggestions? The MB dealer is about at the end of their rope trying to diagnose this issue and I hate having a car that I cannot trust to start whenever it is driven.

UPDATE: 5/20/2024 - MB Service Techs are still baffled and unable to duplicate the problem. Still thinking the likely culprit is the key/DAP interface. Waiting for verification that new keys can be purchased and for how much. There have been over 70 views of this post but no comments to date. Come on guys and gals.....surely someone out there has had a similar problem and is willing to share what they determined was causing the problem.