DIAGNOSTICS on 2001 Volvo S60

HI THERE WHEN I PLUG IN MY U480 OBD2 Car Diagnostic Fault Code Reader Scanner IT SCANS AND SAYS NO CODES IS THIS GOOD OR BAD BUT THE PROBLEM IS I HAVE AN ERRATIC IDLE WHICH IS MOST DEFINATELY THE ETM SO WHY WONT IT SHOW A CODE FOR THAT ANY HELP PLEASE THANKS

by in Ashford, CT on September 21, 2011
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1 answer 1 comment
ANSWER by , October 04, 2011
There are many possibilities for this. I'm not familiar with that scan tool, but it may not be able to read all the codes, which is common for simple OBD scanners. You may also have a dirty ETM, which wont set a code. Is the Check Engine Light on?
COMMENT by , October 09, 2011
no the check engine light is not on the diagnostics show no error codes thanks