Section 433 (Engine Controls - Self-Diagnostics - 6.0L Bi-Fuel & CNG): Introduction

WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Sierra and Silverado vehicles are available as a Bi-Fuel vehicle (RPO KL6) or as a CNG only vehicle (RPO KL8). This alternative fuels article applies to both versions. This article should be used in conjunction with the SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article. This article covers only the Bi-Fuel & CNG self-diagnostics. To properly diagnose and repair this vehicle, follow DIAGNOSTIC STARTING POINT - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, see BASIC DIAGNOSTIC PROCEDURES - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article. If no DTCs are present and a driveability condition exists, see TROUBLE SHOOTING - NO CODES - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).