Check Engine Light Diagnosis & Testing
What is a check engine light?
The check engine light will illuminate on your dashboard when your onboard computer system has identified an issue that could cause an increase in emissions from the exhaust system.
How does a check engine light work?
The computer that operates the engine takes in data from numerous sensors and controls the fuel delivery and ignition system based on that data. The computer monitors the signals coming in and going out. When it measures an anomaly it will register this as a fault, store a diagnostic trouble code in the computer, and turn on the Check Engine Light.
Related symptoms
When the Check Engine Light comes on, you may experience engine performance issues such as poor acceleration, rough idling, and an engine that won't start. In some cases, no abnormal symptoms will be experienced. Whether you experience performance problems or not, a flashing CEL indicates that an engine misfire has occurred. If you continue to drive the vehicle, you may damage the catalytic converter.
What are the symptoms associated with a check engine light?
When the Check Engine Light comes on, you may experience engine performance issues such as poor acceleration, rough idling, or an engine that won't start. In some cases, no abnormal symptoms will be experienced. Other systems like the transmission or ABS can cause the Check Engine Light to illuminate and lights for those systems can come on at the same time. Similar lights may say "Check Engine Soon", "Malfunction Indicator Light" or just "Check". In rare case the engine can overheat.