No, injection doesn't stop damp and is a waste of money.
You could experiment by leaning a large board against the wall to shelter it.
If it is driving rain, shiplap spaced on battens will cure it, and the spacing, plus a kick-out at the bottom, will reduce splashing at the foot of the wall. It must not touch the ground or it will rot. My own shed has a 200mm strip of stainless steel, painted to match, at the bottom of the exposed end.
A cement plinth, or bituminous paint, is often tried, but just shifts the damp above the plinth. Try digging out the trench and filling it with pebbles or cobbles (not shingle). The large stones drain freely due to large irregular gaps so do not splash.
If wind is blowing rain off the edge of the roof, a gutter may help.