Section 127 (Engine Control System - Trouble Shooting - No Codes): Introduction

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Before using Trouble Shooting - No Codes article, check for any related Technical Service Bulletins (TSBs) that may apply.

Before diagnosing symptoms or intermittent faults, follow proper workflow. See DIAGNOSTIC STARTING POINT - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article. If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, proceed to BASIC DIAGNOSTIC PROCEDURES - 1.8L VIBE article. If no DTCs are present and a driveability condition exists, diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

Some driveability problems may have been corrected by manufacturer with a revised Powertrain Control Module (PCM). Check with manufacturer for latest PCM application.

Symptom checks can direct the technician to malfunctioning component(s) for further diagnosis. A symptom should lead to a specific component, system test or adjustment.

Use intermittent test procedures to locate driveability problems that do not occur when the vehicle is being tested. These test procedures should also be used if an intermittent diagnostic trouble code was present, but no problem was found during self-diagnostic testing.