Section 14 (Engine Controls - Basic Testing - CNG): Summary
WARNING: This page is about a different car, the 1998 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to TESTS W/CODES - CNG article. If no fault codes are found in self-diagnostics, proceed to TESTS W/O CODES - CNG article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.