I do not have access to my list of Maserati codes will try to look it up tonight, but, i would have thought the SD3 would have been able to define the problem a little better than that? speed sensors are wheel sensors on the ABS or there is a crank speed sensor on the pulley wheel, and a road speed sensor on the gearbox final drive, but these are all common to both banks so seems unlikely, does the car have CAM position sensors? would these be described as speed sensors? this is an odd code description, the use of the word bank suggests one half of the engine, since that is the normal terminology for one bank of four cylinders, but there is not a unique speed sensor for each bank, so the code itself is ambiguous, which makes me surprised that this is actually what the SD3 reported?