I had heard about the car going into limp mode with the CRD3+ boxes on various other forums in cars that use our engine and that is why I wouldn't spend the best part of 400 notes on one. I ended up getting one from a guy who is going to change to an R for a couple of hundred notes. I've been running program 3 with no problems, love it. The guy I bought it from said that he had the same problem with limp mode.
As far as I know it is just a matter of stopping the car and starting it again. One guy in a SEAT just dipped the clutch, turned the car off and then started it again, all while still moving. The light went off and the car came out of limp mode.