tdci injector no good, should i buy 1 or 4?

[carnut1980]

my 02 mondeo tdci 130 (75k) has fault code p2337, the glow plug light flashes, its running on 3 cylinders it seems, noisy on idle and underpowered, though generally it drives well. A diesel speciaist found the above code, and did a leakage test, which came back ok (even). Injectors 2 and 4 have the code scrubbed off, and cyl 2 has the fault code. Should i buy 1,2 or 4 injectors, as it seems certain no.2 is faulty, but no.4 cant be coded if it has been scrubbed off (was like that when i bought it a month ago)Any advice? cheers

[Blackwhite]

If u will buy new injectors the codes are on it.

Ford recommended replacing all 4 ijectors rather than 1, but it is up to u, u can replace one of them.