DTC 12 Diagnostic System Ready. GMC Truck GMC C Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC C Pickup - 2WD (CNG) 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 DTC 12 Diagnostic System Ready

DTC 12 will always be displayed when the AF ECU enters the diagnostic trouble code retrieval mode. DTC 12 indicates that the ECU is working properly.