Section 12 (Engine Controls - Tests W/Codes - OBD-II): Summary
WARNING: This page is about a different car, the 1995 Lexus LS 400. However, it is still accessible from the selected car via links, so may be relevant.
If no trouble codes are present, driveability symptoms exist or intermittents exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent procedures.