Several months ago I had a panic call from the wife saying her SLK wouldn't start (apparently the fan was running flat out when she turned the key and all the lights on the dashboard were on). She called Green Flag and when they arrived it started without any problems. Varta battery is relatively new and alternator is charging fine. The car has been fine until last week when it cut out on her on the way home from work. No fan running this time and it started after the 3rd attempt. I again checked the battery and alternator which were fine and then checked to see if there was any fault codes of which there were none. After a Google search the K40 relay module seems to be mentioned quite a lot. Apparently it sinks quite a bit of current (there's a 40A fuse on board so a few hundred watts potentially) and some of the solder joints can deteriorate as a result. Has anyone had similar problems either with an SLK or other models fitted with the same module?