What to do when your car’s Check Engine light comes on?

Your car’s dashboard features different signs that indicate the performance of crucial components. One such sign is the Check Engine light, which relates to the function of the engine. Neglecting this light can mean inviting serious problems related to your vehicle. Read ahead to understand what to do when the Check Engine light comes on.

What does the Check Engine light mean?

The Check Engine light means something is wrong with the engine, which is why it’s also called MIL or Malfunction Indicator Light. This is one of the many diagnostic systems in your car that monitor vehicle performance and indicate potential problems.

The turned-on engine light is known worldwide as a signal for checking the engine. The diagnostic system runs several powertrain tests every time you turn on the ignition. Based on the analysis conducted by the system, the Check Engine light may indicate issues in two ways.

1) A steady Check Engine light

Here’s what a steady Check Engine light means.

• When the Check Engine light is steady, your engine is asking for a regular check-up.

• It may not be urgent or significant if you don’t notice anything unusual.

• You can keep on driving and get it checked in some time. 

2) A blinking Check Engine light

Here’s what a blinking or flashing Check Engine light means.

• The blinking light means that your engine needs urgent attention.

• You must park the car at a safe location as quickly as possible.

• Driving with a Flashing Engine light can cause heavy damage to engine components.

• Get your car towed or call a professional mechanic to your location for a check-up. 

Why does the Check Engine light come on?

Here are some of the reasons for the Check Engine light to turn on.

1. Engine malfunctions

A collection of sensors monitor the operation of your car’s engine. So, if it detects a malfunction, the Check Engine light turns on. 

2. Problem with emission

Every car from this decade comes with a wide range of emission equipment. The emission components can include a catalytic converter, gas recirculation, evaporative emission system, etc. Each component serves its purpose, and a problem in any of them may cause the Check Engine light to turn on. 

3. Faulty transmission

The transmission of a car transfers the power from the engine to the wheels. Hence, you can say that engine and transmission assemblies work pretty closely, which is why any faults in the transmission can cause the Check Engine light to turn on. 

4. Issues with sensors and modules

Modern powertrains use many modules and sensors to collect and analyse data and communicate with modules. Any issues in the network, modules or sensors may cause the Check Engine light to turn on. For example, faulty airflow or oxygen sensors can communicate uneven readings that can trigger the Check Engine light. 

5. Interrupted air/fuel delivery 

The function of a car’s engine depends on the accurate flow of fuel and air as well. If the control module notices an increased or decreased amount of fuel or air in the engine, it may indicate issues by turning on the Check Engine light. 

6. Problems in the ignition system

The ignition system uses coil packs, spark plugs and other components to ignite the mixture of air and fuel in the engine. If the spark plugs or any other component in the ignition system becomes faulty, the control module will turn on the Check Engine light. 

7. Open/loose fuel tank cap

While it sounds trivial, an opened or loosened fuel tank cap can affect the performance of the engine. It changes the pressure across the whole system, resulting in higher emissions and reduced mileage. All this can cause the Check Engine light to turn on.

What to do if the Check Engine light turns on?

Here are a few tips to reset the Check Engine light if it turns on. 

1. Tighten the fuel tank cap

Sometimes it’s just the loosened fuel tank cap causing the light to switch on. So, the first thing you can try is inspecting the cap on your fuel tank and tightening it if it feels loose. 

2. Try reducing the load and speed

Excessive weight or speed can put too much pressure on your vehicle's engine. This is commonly seen in small cars driving at high speeds on highways. The additional stress can negatively impact the engine performance and cause malfunctions. So, if you see the engine light turned on, reduce your speed or the load size, if possible, to reset it. 

3. Notice other indicators

If the Check Engine indicator is on, you should inspect other indicators as well to figure out how serious the problem is. The lights or gauges on your vehicle’s dashboard will tell you about overheating, low oil pressure and other problems. In such conditions, you should immediately shut off the vehicle engine and park your vehicle as quickly as you find a safe place. 

4. Run diagnostics 

If your vehicle has a built-in diagnostic system, you can use it to understand the issues when the Check Engine light turns on. Or, take it to a professional mechanic, who would understand the reports generated by the built-in diagnostic system and decide the suitable repair steps. 

Frequently Asked Questions (FAQs)

Here are a few commonly asked questions answered about the Check Engine light and related issues.

Can I drive my car with the Check Engine light turned on?

You should be attentive to how the vehicle is performing when the Check Engine light is on. If there are strange sounds or surges in acceleration, you should find a suitable place to park your car. In case there is nothing unusual, you can keep on driving even when the Check Engine light stays on. However, you must avoid sudden gear shifts and uneven acceleration. Try to drive slowly and steadily to a repair shop and get the vehicle checked by a professional.

What is the catalytic converter problem in vehicle engines?

The catalytic converter converts toxic gases like hydrocarbons into less harmful gases. Any fault in this component can cause a reduction in vehicle mileage. The Check Engine light will turn on in this situation.

Can oxygen sensor failure cause the Check Engine light to go on?

An oxygen sensor monitors the amount of unburned oxygen available in the exhaust. It allows the sensor to figure out the fuel-burning efficiency. A faulty sensor can impact the diagnosis or send poor performance readings to the module. This can trigger the Check Engine light.

Do all cars come with built-in diagnostic systems?

No, all cars don’t come with a built-in diagnostic module. However, several automakers, like Ford, Jaguar, Hyundai, Land Rover, etc., offer built-in diagnostic systems with their modern car models.

Disclaimer: The content on this page is generic and shared only for informational and explanatory purposes. It is based on industry experience and several secondary sources on the internet, and is subject to changes.

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