RW> If you have a scanner that clears the codes, they can't tell if there was   
   RW> a code in the computer. If you disconnect the battery, there's still a   
   RW> history of the code in there, but no CEL. I have an HP Tuner, which can   
   RW> clear codes as well as re-write most of the look-up stuff that's in   
   RW> there.   
      
   Yes, my scanner and computer program can both clear the codes.  The issue is   
   that it "resets" the tests.  At least it did on my daughter's Cougar.  The   
   catalyst tests (I believe there are three of them).  The last test takes   
   several days to complete after a reset or clear.     
      
   If you take it to emissions after a clearing the code, the computer re-starts   
   the tests again.  They can tell at the emissions station that the tests have   
   not completed - so it shows to be "not ready" for testing.  They don't fail   
   you, they just tell you to come back in a week.     
      
   - Mark   
      
   --- WWIVToss v.1.50    
    * Origin:  http://www.weather-station.org * Bel Air, MD -USA (1:261/1304.0)