Carry Out On-Board Diagnostics (KOEO, KOER)
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. 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 INTRODUCTION - CNG, FLEX-FUEL & GASOLINE .