Monitored Emission Control Systems
WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
The CNG controller supports HO2S monitoring. The I/M tests that are supported by the gasoline controller are the same as those in a non bi-fuel vehicle.