Karl Disco 2:
There are a couple of reasons for this.
1) most overlooked one is to check the battery, if not 100% the voltage could drop low enough when starting and cause it to go into limp mode (flashing M&S with flashing D)
2) Water from the aircon drips directly on the gear position switch causing a short, this then makes the EAT ECU think that it selected two gears causing limp mode.
First have it checked with a testbook to see if any error codes exist. And then take it from there. Also remember to visually inspect the plugs as well as buzz(Check continuity) all the wires from the ECU to EAT ECU which is located under the passenger seat. You will also need to remove the gear lever and the console. When you remove the gear lever dont twist it at all, as you will break it. IT JUST PULLS OFF!!! with quite a bit of effort.
Folks I know of replaced a perfectly good box because of a plug. so check visually as well as electronically and with TESTBOOK.