Check Engine Light On? – Get It Diagnosed Free

Most of us start to freak out when the “Check Engine” light” comes on.  We take our car to a mechanic.  The mechanic charges around $80 to run diagnostics to find out what the issue is.  To be clear, the $80 is to just run diagnostics.  He would then provide a quote to fix the problem.  The whole thing feels like a rip-off.

Check Engine Light

When the Check Engine light comes on, it means that the vehicle’s engine has detected something wrong. It could be something simple such as a faulty gas cap or something serious such as a misfiring engine.

You can connect an OBD-II reader or scanner to a connector below the steering column to get a code.  The code tells you what the problem is.

OBD-II: On-Board Diagnostics System (Version 2)

Federal law requires all vehicles purchased in the US after 1996 to have an On-Board Diagnostic System II (II refers to version 2 of the system).  OBD – II can diagnose vehicle problems through a diagnostic computer.  Problems detected by the OBD-II include simple things like forgetting to replace the gas cap tightly to complicated problems such as powertrains, emission, or other vehicle problems.

When the “Check Engine” light comes on, you can connect a device called the OBD-II reader or scanner to read the code. You can find the list of codes for OBD-II .

Free Diagnostics at Auto Parts Stores

Honest mechanics will run a free diagnostics for you.  But those are rare to find.  In most cases, you have to pay to get your diagnostics done.

Auto parts stores like Autozone, NAPA, or Advance Auto Parts will run diagnostics for free.   These stores target DIY’ers and hope that if they diagnose the problem, the car owner will buy parts from them to fix the problem.  Most auto parts stores also rent basic tools for free.  If you are someone who can fix minor problems on your own, it can save you a lot of money.

In some states, these auto-parts stores will also clear the code for you. Clearing the code does not fix the underlying problem.  In most cases, the Check Engine light will come back on again after you drive for a few minutes.

You can even buy your own OBD-II scanner for around $20.  It will come in handy when the Check Engine light comes on in your car.  The OBD scanner pays for itself the first time you use it.

Most Common Problems

The most common problem when you see a Check Engine light is a loose gas cap.  Tighten the gas cap and in a few minutes, the light should go off.

If you didn’t have a loose gas cap, it’s best to run the OBD-II scanner to find out what’s wrong.

Bottom Line

When the check engine light comes, most people fear the worst.  Mechanics and dealerships charge around $80 just to run diagnostics.  Auto parts stores such as Autozone, NAPA, or Advance Auto Parts will run diagnostics for free saving you money.  You can also buy own OBD-II scanners and find out about the problem using the list of OBD-II codes.


Has the Check Engine light come on in your car?  What did you learn?  How did you fix the problem?

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