My 2005 C230 K died on me going down the road. My #53 fuse (ECU Fuse) was blown.I replaced it and as soon as the car is put into key position 2 it blows again and then the cooler fan turns on full speed.
I was thinking it was a short between the Front SAM and the ECU but now i'm not sure because if I unplug the ECU and turn the key to position 2 the fuse dose not blow but if I leave the key in position 2 and plug the ECU back in it blows again. Any help would be appreciated.

 

I opened up the ECU last night and everything looked normal I found no evidence of a short or any discoloration.

 

How severely are your camshaft sensors leaking oil? The electrical lines leading from these sensors feed right into your ECU and there have been cases where the oil got into the ECU and causes symptoms similar to yours.

 

There not leaking I took care of that about 20,000 miles ago the ECU plugs look good.

 

My issue turned out to be a short in the #2 coil which caused the #53 fuse to blow. The #53 fuse provides power to the ECU and the coils so once the fuse was blown the ECU lost power and that caused the Cooling Fan to run on High speed.