Diagnostic Trouble Code (DTC) Memory

When the engine control module (ECM) detects a fault, the diagnostic trouble code (DTC) is stored with a qualifier and status in the DTC memory in the control module. For certain types of diagnostic trouble codes (DTCs), the missing signal is replaced with a substitute value so that the system can continue functioning.

If the fault disappears, the diagnostic trouble code (DTC) will remain in the DTC memory for some time, but its status will change.