Medium and Heavy Trucks
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Hi, My name is***** will be glad to try and help. Fault code 73 is for injector circuit 3 and 4. Check the injector harness and connector pins for damage and a potential harness issue. If the harness checks ok try moving the injectors to another location to see if the problem moves with them. Fault 72 would be for 1 and 2 and 74 for 5 and 6. If the fault remains as code 73 with a good harness and the injectors swapped with 1 and 2 for example you would have a problem with the injector drivers in the ECM and the ECM would need to be replaced. Let me know.