Viewing Diagnostic Codes The screen displays a message indicating that the data is being requested, then displays the data. For example: CODES LAST CLEARED AT 2.1 ENG HRS CLEAR CODES NOW? YES [NO] 3 Select Yes . The screen indicates that the codes are being cleared. CLEARING FAULT CODES PLEASE WAIT... Once the codes are cleared, the screen returns to the Diagnostic Codes menu. DIAGNOSTIC CODES ----Selections---- CLEAR CODES 4 Press to return to the Engine Menu . Detroit Diesel Application User’s Manual 21