What does a check engine light mean?

Decode Your Check Engine Light: Act Now to Prevent Costly Repairs

The check engine light (CEL) is one of the most common and often dreaded warning indicators on a vehicle’s dashboard. When it is illuminated, it can evoke feelings of anxiety and uncertainty, especially if you’re not sure what it means or how serious the issue might be. This article will help you understand what the check engine light means, the common causes for its illumination, and what steps you should take when it appears.

Don’t Freak Out If Your Check Engine Light Comes On

If your check engine light isn’t flashing, the engine is running smoothly, and the transmission is shifting normally, this won’t be a major repair. In most cases, the light is on due to a faulty sensor, and those repairs aren’t cripplingly expensive.

What To Do When The Check Engine Light Comes On

Get the trouble code(s) read at any auto parts store; most will read the trouble code for free

But keep in mind that they’re in business to sell parts. So they’ll recommend replacing whatever part is listed in the trouble code. If you follow their advice, you’ll replace a lot of perfectly good parts and still have the code.

The part mentioned in the code may be telling the truth and the root cause for the bad data is due to some other issue. A lot of DIYers have wasted a lot of money replacing whatever part was listed in the code without doing any diagnostic work. If you don’t diagnose the problem, then you’re just throwing parts at it.

A trouble code is not a diagnosis: It’s just a starting point

A trouble code is not a diagnosis. It’s like getting a high blood pressure reading at the Doctor’s office; you know something is wrong, but you don’t know the cause. So, the Doctor orders tests to discover the cause, but the Dr. doesn’t automatically recommend replacing your heart.

How to diagnose the problem yourself

Every good shop manual lists the diagnostic procedure to discover the root cause of a trouble code. If you want to diagnose the problem yourself, invest in a short subscription to a professional shop manual like alldatadiy.com or eautorepair.net. Or, call your local public library and ask if they offer free access to online repair manuals.

To diagnose a trouble code, you’ll need a multmeter and possibly a scan tool. If you don’t own those tools or don’t know how to use them, take your car to a shop for a professional diagnosis.

How much does it cost to get a professional diagnosis?

Most shops charge a minimum one-hour diagnostic fee to determine the cause of the check engine light. A real diagnosis involves some testing; it’s more than simply reading the trouble code again. Only a hack technician would make a diagnosis with just the code.

Can you still drive with a check engine light on?

In most cases, yes. If the check engine light isn’t flashing and your vehicle is driving normally, you can continue driving until you have an opportunity to get it into a shop to be diagnosed.

However, if the check engine light is flashing, that’s an indication of a serious misfire that could cause expensive damage to your vehicle’s catalytic converter. Converter replacement can cost thousands. So if your light is flashing and you can’t get it to stop flashing by backing off on the accelerator pedal, pull over can get it towed to a shop. A tow will cost a lot less than a new catalytic converter.

What are the most common causes of a check engine light coming on?

Misfires, caused by ignition, fuel or mechanical problems
Emissions issues caused by leaks in the evaporative emissions system or exhaust system
Air/fuel-related problems caused by air/vacuum leaks or faulty oxygen sensors

©, 2023 Rick Muscoplat