Want to know about detroit 14L engine check

i have purchased 2007 Columbia with EGR Detroit 14L . This truck shows engine check light steady n dashboard.My mechanic scan codes it shows injector1 response slow.But this truck have all injectors purchased from Detroit last year and installed..The seller provided me invoice for them.... but he said after installed all new injectors still light comes and shows same code of injector 1..... But truck have no power issue ,,,Running smooth since he installed all injectors about 18 months ago ,,, My mechanic tested injectors one by one putting load on injectors,,,,,,All injectors have same response working fine......No other code shows for engine check....... May be this is injector harness???? or I can keep continue driving....Please help me for getting away from future problem

 

yes it again comes up that's why mechanic checked injectors one by one with computer he was putting load and at the end he print report that all injectors working perfect

 

Looks like its original harness

 

I really appreciate brother thx. Yes you right bcs truck have 9,50,000 miles on it. Previous owner should replace these but anyhow. I will do this.

 

NO ECM IS GOOD ALWAYS THESE KIND OF ISSUES RELATED TO HARNESS COMMONLY