The Check Engine Light Demystified

There’s one little yellow light that strikes fear in the heart of every driver. It casts a shadow of doubt over your whole vehicle. Will this be something straightforward or will the repair bill put you in debt?

The Check Engine Light has long puzzled drivers with its vague warning. When it illuminates, it's unclear if you should continue driving or get your car towed. Here’s everything you’ve wanted to know about the Check Engine Light:

What the Check Engine Light Does

The Check Engine Light has one purpose: to tell you when you have a problem. That’s all. It doesn’t tell you what the problem is; a technician will have to perform a diagnostic scan to check the affected system. It only indicates that something isn’t working properly.

The Check Engine Light is also known as a malfunction indicator light. It’s shaped like a motor and is yellow in color. Most vehicle systems run self tests under certain operating conditions, and the results are reported to their respective control modules. If a self test fails under certain parameters, your car’s Check Engine Light will come on. It could be an engine, transmission, or emissions system that didn’t pass the test.

What Does the Check Engine Light Mean?

There are two different ways the Check Engine Light can come on: solid or flashing. They mean two different things.

If the engine light comes on and flashes, that indicates an immediate concern. You need to find a safe place to pull over and turn your vehicle off. You may want to consider getting it towed to the shop. A technician needs to diagnose the concern at the absolute earliest convenience to prevent damage to your car. A flashing Check Engine Light is serious business.

If the engine light comes on solid, it may still be a reason for concern, however it doesn’t immediately need to strike fear in your heart. A solid Check Engine Light can mean something like a loose gas cap, or it can indicate a more in-depth problem like a fuel, timing, or transmission issue. Get your car diagnosed, although the urgency isn’t the same as if the light was flashing at you.

Common Reasons the Check Engine Light Comes On

The reason for an engine light can be a risk of catastrophic failure or something requiring immediate attention, or it could be nothing at all. As the car’s systems run self-tests, it is possible that a test fails and the engine light comes on, and the next test passes. The Check Engine Light may not turn off as soon as it passes, and it may not even turn off until a technician clears the code even though there is no repair required at all. Common reasons for the Check Engine Light are:

  • The gas cap was left loose when refuelling
  • Emissions-related sensors, such as oxygen sensors, have failed
  • Engine timing problems, most commonly with variable valve timing
  • Transmission failure codes
  • Engine misfire codes
  • Catalytic converter problems

There are literally dozens, if not hundreds, of other reasons for the Check Engine Light to come on. If it illuminates, have it checked out expediently. Don’t take unnecessary chances if it feels like the vehicle is not operating in a safe manner. Have your vehicle towed to the shop if you don’t feel safe driving it. If the Check Engine Light is flashing, it is in your best interest to cease driving until the light has been diagnosed and repaired.


Next Step

Schedule Check Engine Light is on Inspection

The most popular service booked by readers of this article is Check Engine Light is on Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

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Keven

7 years of experience
118 reviews
Keven
7 years of experience
Mazda Protege L4-1.5L - Check Engine Light is on - Tacoma, Washington
Kevin is a focused man who has no doubt about his job. Quiet,friendly,respectful. I have nothing but the best to say. Thanks again for your help.
Toyota Sienna - Check Engine Light is on - Spanaway, Washington
He was very efficient, very knowledgeable and very sweet. Thank you for your time and your patience with my vehicle.

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L Hybrid - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.

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