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.
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.
Can I drive with the check engine light on?
Whenever the Check Engine Light is on there's a possibility the engine is emitting excessive emissions out the tailpipe. In extreme cases other parts in the system can be damaged, like the Catalytic Converter or Oxygen Sensor. Whether you experience performance problems or not, a flashing CEL indicates that an engine misfire has occurred. When this happens you should pull off the road and not drive the vehicle as this will damage the Catalytic Converter, which can cost over $1000 to replace.