Already posted in the 231 section. No one has any ideas. found this post because of the error code 30g, one of the codes retrieved by the dealer. Exactly the same symptoms though. the problem is intermittent in that it arises after the car sits overnight, then after starting and revving the engine for a while (or maybe just passage of a few hours....can't tell) works well enough to go to dealer. twice they said it was a dead main battery. first time replaced it, second time disconnected the bladder pump for the seats saying it was running all night because of a hole in the bladder, and drained the battery. about two to three weeks between episodes. this time it stayed at the dealer until they got the problem when they started it in the morning, and they read a 30g error code. no word after almost a week as to what is actually wrong with the car. btw, when you have this happen the wheels lock. they have to put dollies under the wheels to drag it out of the garage and onto the tow truck. most tow companies in my area don't have the ability, but I found one who does, and who is an MB enthusiast with a 231, S sedan, E 4, and who does his own work. he was puzzled by the problem as well.
Any help you can offer is welcome. the tech at the dealer has obviously been puzzled as well.
Last edited by 1309w; Jul 31, 2019 at 11:04 PM.