GMC Troubleshooting Questions? Ask a Mechanic for Answers
I need you Vin nr. Also I have to know if software update was performed on engine computer. Here at my shop we have a lot of problems with does trucks and Def system. Poor quality might also mean that your injector is not injecting sufficient amount of fluid. Your nox Sensors might read wrong. Or there's not sufficient Def pump pressure . So catalyst doesn't occur and computer recognize it as poor Def quality.