Been lurking for many years now and learning a lot. Fantastic community, probably the best of its kind on the net. Thanks to the webmasters and moderators!

Well, the time has come for me to ask for help. I've seen several posts from Mercedes owners who have this problem: cruising at highway speeds ~70MPH after about 30 minutes ASR light comes on and car goes into limp mode. Turning car off then on corrects the problem. Also, as a side note, engine light has been on for over a year, but no other symptoms. The ASR and limp mode happened once over a year ago and I thought it was a fluke. But now for the last month it has happened four times.

I'm using a local shop and they hooked my car to an Alldata diagnostic system. The readings were as follows:

17,18
Test scope: Serial data bus (CAN)
Possible causes: Data line, DI control module (N1/3)

They reset the computer, it faulted (engine light on) and got the same readings again.

They tested the data line, it passed. They say now, its the computer. Replacement > $2K.

Are they on the right track? I saw that other lucky owners on this forum were able to fix the problem inexpensively by replacing:
- Transmission shift position sensor
- Brake light switch
- Over Voltage Relay

Has anyone had success by replacing the fuel actuator?
Is the Alldata system reliable?
Will a factory shop have better diagnostic equipment?
Is it worth trying the three above options and if so, which choice is the most promising.

Thanks!
Walter