BMW E60 525d LCI glow plugs error

[gadbt]

Hi,
I know its common for glow plug module to fail so i replaced it along with all 6 glow plugs 3 months ago. Its hitachi module and everything was fine until today when i checked for code errors. Now every time i start the car or turn the ignition on i either get no errors or i get glow plug errors but the catch is that every time is different glow plugs but mainly the even ones. Sometimes its just second cylinder glow plug, sometime 2 and 4 and sometimes 2,4,6. Today first cold start i got no error codes and when i started the car after 2 hours i got 2nd cylinder glow plug error. Someone with this experience may be the wiring or connectors i dont know. Please advice i dont want to immidietly change everything again.It says in the title but the car is E60 525d lci 2008. (3.0L 197hp). I have no issue with cranking whatsoever. I know that dpf filter will no regenerate if 3 or more glow plugs are faulthy so that my main concern.