I have a 126 model with the 116 engine, so I don't know if they are even related at all in design. I do know that you described my symptoms to the letter and that was what was wrong with my car. It is a little black box that holds a circuit board. Solder joints sometimes break on that board, or a part burns out and causes it to fail. I have found remanufactured boards for $90. You first need to find out if that is definetly it, and on this car, I am the wrong guy to talk to. Sorry if I detracted from your solution.