Engine Controls - Self-Diagnostics: General Description

This vehicle is equipped with an engine and emission control system which are controlled and monitored by the Engine Control Module (ECM). ECM has an On-Board Diagnostic system which detects a malfunction in this system and abnormality of those parts that influence the exhaust emissions. When diagnosing engine troubles, be sure to have a full understanding of the On-Board Diagnostic system.

There is a close relationship between the engine mechanical, engine cooling system, ignition system, exhaust system, etc. and the engine and emission control system in their structure and operation. In case of engine trouble, even when the Malfunction Indicator Lamp (MIL), displayed on instrument cluster as "SERVICE ENGINE SOON" lamp doesn't illuminate, it should be diagnosed referring to this flow.