Vauxhall Workshop Service and Repair Manuals

Electronic System Specific Information

• Trouble Code Features
  In a few cases, the diagnostic tester may display a trouble code status or description that looks unfamiliar:
  
  Trouble Code Status:
  Instead of the known PRESENT, NOT PRESENT (and INTERMITTENT) message, you may read UNKNOWN DTC in the tester display. This tells you that the diagnostic software or control unit contains a piece of incorrect information that is unknown to the diagnostic tester and that it is unable to read or evaluate. Both the trouble code number and the trouble code text are not changed in this case.
  
  The above mentioned special cases can not be removed by means of a diagnostic tester function.