Carry Out On-Board Diagnostics (KOEO, KOER)
WARNING: This page is about a different car, the 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
After a road test, with the vehicle warm and before disconnecting any connectors, carry out the Quick Test using the scan tool. Refer to SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE .