Diagnostic Trouble Codes (DTCs)
WARNING: This page is about a different car, the 2007 Dodge Sprinter. However, it is still accessible from the selected car via links, so may be relevant.
With OBD II, different DTC faults have different priorities according to regulations. As a result, the priorities determine MIL illumination and DTC erasure. DTCs are entered according to individual priority. DTCs with a higher priority overwrite lower priority DTCs.