what does the codes 11 & 31 mean my friends subi has stopped twice for no apparent reason but these are the codes it showed?

Code 11 is the crank angle sensor

Code 31 is the throttle sensor

 

more info on all the rest of the codes can be found on my site.

 

Have your friend reset the ECU, again the procedure can be found on my site, and see if the codes come back. If one or both come back, then I would investigate further.

so for the crank angle sensor when it says in the failsafe area that there is none does that mean it stops? :-\

pretty much, yeah....the car won't run without it.