Engine Control System - Self-Diagnostics - 4.2L: Summary

If no hard fault DTCs are present, driveability symptoms exist or intermittent DTC(s) exist, proceed to SYMPTOMS or INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.2L BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.