why does my engine management light keep coming on and going off

hi i have a fiat panda 06 auto, acouple of weeks ago i went through quite a deep puddle, alittle while later engine management light came on but after four turns of the ignition it goes off, but a little while later it will jugger a bit light will come back on. took to garage got diagnostic done , code came up for fuel injection l did have the the spark plugs and leads replaced by the garage, it did resolve the problem for 2 weeks but has now come back on, took back to the garage done another diagnostic the same code came up as before fuel injectors, would appreciate it if would let me know possible causes many thanks pauline