Automotive Q & A

Knowledge Database - Engine

Question: How do engine diagnostics work?

Answer: Since 1996, every vehicle that is built to be sold in the United States must have the OBD-II System. The OBD (On-Board Diagnostics) System is a device that detects problems in your engine. The system was put in place to help control vehicle emissions. Basically, this system can detect and inform the driver of malfunctions in the engine. It will send a message to your engine’s ECM (Engine Control Module) computer system. The ECM is in charge of controlling many of your engine’s processes including air/fuel mixture and emissions. The ECM System keeps your engine running efficiently while keeping emissions low. The ECM uses sensors to monitor your engine, adjust emissions, and/or engine timing when necessary; it will inform the driver when something is wrong with the vehicle by triggering your “check engine” light on your dashboard. If your OBD-II System detects a problem, it will record and store the corresponding code for the problem, which can be accessed by a technician. A trained technician can hook up his/her computer to your ECM System to receive the error code and diagnose the problem. The OBD System makes it much easier for a technician to determine what is actually wrong with your engine.

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