Check Engine Light

What causes your Check Engine Light to come on?

Almost everyone has been driving along at some point when their little yellow “Check Engine” or “Service Engine Soon” light pops on with no warning. Even though most people have experienced it, the check engine light is one of the most misunderstood lights on the dashboard, and knowing what to do to resolve it takes an understanding of what makes it come on.

What is a Check Engine Light?

The check engine light is part of your vehicle’s engine management and onboard diagnostics system. The lamp may read “Check Engine” or “Service Engine Soon”, or may simply show a picture of an engine(shown at right), possibly with the word “Check” or “Service”. The light is connected directly to the engine control module (ECM), the computer that controls the vehicle’s engine. The ECM turns the light on, and only when it detects that something is amiss. The ECM is a computer, so the only way it can tell what is happening in your engine is through electronic signals from an array of sensors mounted throughout the vehicle. It uses the information it gathers to control the engine’s operation, and to diagnose problems. Since this information is being transmitted electronically, electrical glitches, loose connections, or faulty sensors can confuse the ECM and cause a Check Engine lamp as well.

The information gathered by the ECM tells the computer about atmospheric conditions, driver inputs, engine parameters, exhaust emissions, and other vehicle systems. This info is used to control many aspects of the engine’s performance, including the amount of fuel injected into the engine, ignition timing, idle speed, and throttle angle on most new vehicle. When the ECM senses an error and turns on the “Check Engine” light, the computer will often enter a “limp-home” mode, which controls the engine using the available good information, but does not offer the best possible fuel economy and engine performance. The sophisticated ECM can compensate for many small problems, meaning that while you may not feel a difference in the way the vehicle drives, fuel economy is likely going to be affected, and other components may be damaged by long term driving with the check engine lamp on.

At Richardson’s Auto Care, we have the required computers and up-to-date software to interface with your car and diagnose your check engine lamp problems. Our technicians specialize in thoroughly diagnosing your computer’s faults the first time, to save you from having to purchase unnecessary parts or repairs. Call us at 972-853-2000 or e-mail to schedule an appointment to have your check engine lamp diagnosed.