On all modern vehicles there is a computer that controls the way the engine operates, this computer is called Electronic Control Module, or ECM. The purpose of the ECM is to maintain the engine running within emissions limits and at top efficiency. With the very strict emission regulations of today, this is not an easy task to achieve. Precise and constant adjustments to match various conditions of the engine must be made by the ECM in regards to speed, load, engine temperature and others.
How the ECM works:
A number of sensors are available that provide the ECM with the information it needs, such inputs are engine and ambient temperature, vehicle speed and load. The ECM makes adjustments by advancing or retarding the ignition timing, adds or subtracts fuel or increases and decreases the idle speed.
In the exhaust, before the catalytic converter, an oxygen sensor monitors the quality of the combustion produced in the cylinders. The sensor produces a feedback that is then used by the ECM to make fine adjustments to the fuel-air mixture with the objective to reduce emissions. After the catalytic converter, another sensor in the exhaust monitors it's efficiency
Other additional emission control systems exist, such as the Evaporative System, or EVAP. The objective of EVAP is to prevent vapors of gasoline, from the gas tank, from being released into the atmosphere. There are also a number of sensors and actuators that are controlled by the ECM.
The operation of sensors and other engine components is constantly tested by the self-diagnostic capability of the ECM. If one of the signals is missing or if it's not in the normal range then the Check Engine light is illuminated and the Diagnostic Trouble Code, DTC, is stored in the memory of the ECM. The Check Engine light will be illuminated also if a mechanical component, such as the EGR valve, fails.
With a special scan tool, the stored code can be retrieved by a technician, that will then know only a direction where to look for. The code doesn't tell specific information about the failure, certain tests have to be performed for each code, in order to find the exact cause of the problem.
Check engine are two words that no driver wants to hear or see, but sometimes it becomes a reality. One of the most aggravating things about those words is that when the check engine light pops on, there is still not a lot of information you can gather from it. The check engine light is designed to come on if anything is not absolutely perfect under the hood. This means that you have no reason to panic when you see it light up because it could be something so minor.
One of the most common reasons that you will see the check engine light come on is also one of the easiest things to fix; your gas cap is not screwed on tight enough. This may sound silly, but they mean it when they say that the light comes any for anything. Some cars are designed to measure how much pressure is building up inside your gas tank. So, it sets off an alarm in your car system if it strays a certain percentage from the average. This mathematical and technical information does not matter; it just means that your gas cap is not on tight enough. If this happens, you should tighten the gas cap, but keep in mind that it can take up to a week or more for the check engine light to go out on the dashboard.
Another reason that your check engine light may have appeared suddenly is because your engine got wet in a place that it should not be wet. If there is any type of electrical problem under the hood at all, then it will surely set off one of your cars many sensors that alert the car that there is a problem. So, be aware that this can happen when it rains a lot because it could be dripping water into unusual areas like on the spark plugs. Also, you should not spray your car under the hood with a high pressure power washer because you run the risk of getting water into every crevice of the car and damaging something that should not be getting wet.
Spark plugs are something under the hood that can be very problematic, especially pertaining to the check engine light. As your spark plug wires start to get older, they can develop little cracks which are not good because they let out little bursts of electricity. So, if your check engine light comes on and your gas cap is on tightly, then you should probably check the spark plugs for any issues.
Both Dalvin Rumsey & Phoenix Delray are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.