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Automotive Diagnostics

Check Engine Light.

CHECK ENGINE LIGHT (also known as MIL) as know by many, is usually located on the dashboard of the driver’s side. it is one of the function lights that indicates a change in the normal working condition of the Vehicle Engine and other components.

Check engine light
Check Engine Light


Older cars usually had the light as the only information indicating a change in the normal working condition of the car engine. But for modern cars, there are other display that helps give more information about the malfunctioning of the engine been displayed on the dashboard.

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Whether you are using a old car or a new car, one thing is sure, which is that the when the Check Engine Light is ON, the car needs to go in for diagnostic.


Tips to prolong your car lifespan;
Diagnose your car anytime you see the CHECK ENGINE LIGHT ON
Diagnose your car anytime you experience an accident or mechanical damage.


Diagnose your car anytime you notice any changes and noise that is unwanted.


This shows how important doing diagnosis when you notice the Check Engine Light.

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The Check Engine Light turned ON can be caused by several malfunctioning in the Engine. Some of these malfunctioning includes; misfiring of Cylinders, Combustion chamber problems etc.

Check engine light

Code Readers and Diagnostic scanners
Now let’s talk on the difference between a DIAGNOSTIC Code Reader and a Diagnostic Scanner as regards erasing of Check Engine Light.


The Code Reader is used to read fault codes only, some Code Reader can also clear fault codes, i.e. MIL. the function of a Code Reader is limited.

A Diagnostic Scanner does not only read fault codes and clear MIL, some advance type also explain details about the fault, in fact very good one’s are also used for reprogramming of vehicle computer. Very powerful ones also show you the faulty system or parts, they recommend repairs options, some even teaches you how to disassemble and reassemble such faulty parts. Programmers and engineers are designing more powerful diagnostic scanning tools daily.

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Current and Stored faults codes
Check Engine Light is prompt on by various malfunctioning in the Engine system, it is an indication that the car needs to go for proper Diagnostics. It can be erased or cleared from the dashboard, using a diagnostic Scanning tool or a code reader.


The Check Engine Light may not be erased when you try to erase it at all times. All fault code cannot be erased.

Fault codes which are stored and current cannot be cleared by a scanning tool, until the faulty system has been repaired, then the fault code can then be Erased.


Current: this means that the component or system has a fault.
Current and Stored: this means that the component or system has a fault, and it must be replaced (that is it has a mechanical damage) before the fault can be cleared.
Event: there is an fault history about the component or system.


Fault codes with current and event may be erasable.
So you now have a little understanding of the various types of fault code, and those which can be cleared.

Asoro The Automotive Consultant

By Asoro The Automotive Consultant

Osasumwen Gideo Asoro is an Auto Expert and CEO Asoro Automotive, He owns a Bachelor Degree in Mechanical Engineering from University of Benin. He specializes in Automotive Diagnostics, Repairs, Sales and Consultancy. He is an Automotive blogger and YouTuber, he has also authored many best-selling books on Automotive Technology which are available on Amazon and other major marketplaces. He also creates Online course which are available on Udemy, Teachable and others.

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