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Safety in Driving a Car with a Check Engine Lights On

Safety in Driving a Car with a Check Engine Lights On

Imagine driving around with a faulty car without a hint that something is about to go very wrong – you end up damaging your car more, your car suddenly stops in the middle of a heavy traffic or worst you get into an accident. Fortunately every car has a way of warning you. At your car’s dashboard an easily recognizable warning light in the shape of an engine can be found. Usually it has the word “Check” in yellow or red. Its main purpose is to notify the driver that one of the car’s sensors is not correctly functioning.  

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The warning light also called the Malfunction Indicator Light (MIL) or “tell-tale” warns that there’s a malfunction as detected by your vehicle’s computerized engine-management system. When something becomes faulty with the complex collection of components and sensors in your vehicle it triggers this light to come on.

And if the Check Engine Light does come on, can you safely keep on driving to check on what’s wrong later when time is convenient or continue driving just to get to the nearest mechanic? Or best to just hit the brakes altogether. The deal is whenever you start your engine you’ll automatically notice that the said warning light glows, but it will only do that temporarily – usually for around six seconds – and turn off. That means you keep on driving and it’s going to be one ordinary day on the road. It means no problem was detected. But what if the light continues to come on or what if it starts to blink?

To not panic and know exactly what to do, you need to be informed of the stages of the warning light.

(Stage 1) Steady Light- A steady light means minor fault detected

A solid or steady Check Engine Light can mean a loose gas cap, or it can also mean a more in-depth problem like a transmission, fuel or timing issue. But if it did turn on after fueling up chances are it is a loose gas cap. A lot of new car models already have a “Loose Gas Cap Light,” while those that aren't current don't have the feature yet. If the gas cap was left loose or was left off the car’s computer would detect a leak on your evaporative emissions system turning on the Check Engine Light. So check the gas cap. First, take it off and proceed to reinstallation. And then drive your car once again to see if that resolves the problem. You may have to restart a couple of times for the check engine lights to go out. If that doesn’t resolve the problem you will have to get your car diagnosed, although there’s no immediate cause for alarm compared to if the light was continuously blinking. The fix could still be straightforward and cheap.

Another reason for the light to come on is an issue with the Oxygen Sensor. Its role is to measure the amount of oxygen present in your exhaust system. The data is then communicated to your car’s computer for it to adjust the air and fuel mixture of the engine. Issues with the oxygen sensor will cause the car to use up more fuel and in turn produce more emissions. This issue is considered to be less alarming.

As long as your car isn’t running strangely (e.g. presence of strange noise from the engine, smoke coming out) you’re safe to drive the car for the mean time before setting a more convenient time to have your car checked out.

Stage (2) Intermittent Blinking (Flashing comes and goes)

The warning light only blinks whenever the problem is encountered, meaning there’s a soft failure. A good example is when connectors become loose or already broken wires become disconnected whenever a car goes over an irregularity or a bump on the road. The problem may still not be critical. The problem comes and goes causing the light to blink, stop and then start blinking again. 

(Stage 3) Continuous Blinking or Flashing Light – means severe fault detected.

When the check engine light blinks continuously it indicates that a critical problem is present that can cause serious damage if not attended to immediately. You need to stop driving and have your car towed to a service mechanic.

The Check Engine Light usually flashes when the computer detects the following issues: 

  • Issues with the mechanics of the engine or with the fuel system 
  • Faulty injectors, regulator or fuel pump
  • If there’s an increase in emissions
  • Presence of vacuum leak, hose or gasket issues
  • Bad oxygen, EGR valve, or EVAP sensor
  • If there are electrical connection problems like broken wires and corrosion

The Check Engine Light will flash when there’s an Engine Misfire indicating that it’s dumping enough unburned fuel into the exhaust system of the vehicle. This could result to a very major issue because it can abruptly increase the catalytic converter’s temperature. An elevated temperature could cause damage to the converter requiring a major repair that could be very costly. And worst it could even start a fire in the vehicle.

There are three major reasons why engines misfire. The top reason is a defect in the ignition system that is fortunately the least expensive to repair. A fuel system defect comes in as the second potential cause which costs a little more to repair because it involves the replacement of pricier components like the fuel injectors. Lastly, the vehicle could be suffering with an internal engine defect that costs the most to repair.

Other most common reasons for the Check Engine Light to come on:

Issues with the Catalytic Converter

This car component’s role is to control the emissions in your car’s exhaust system as it converts carbon monoxide and other harmful gases into less harmful byproducts. So if the catalytic converter is not working as it should you will be wasting money on fuel and not only that, your car’s performance will also be affected. The bad part is that this component is costly and with some cars you have to replace four of them. So if there’s a damage to this car part it is best to attend to it immediately.


Issues with the MAF (Mass Airflow Sensor) 


This sensor aids your car to distinguish the amount of fuel to be added in accordance to the amount of air coming into the motor. Issues could surface from having a dirty air filter or from it not being properly installed. A faulty MAF sensor is not an immediate cause of concern. But until you have it replaced by a professional mechanic there’ll be a decrease in fuel economy and you will continue to experience poor car performance.  With this a reduced gas mileage and stalling can indicate an MAF problem. Other signs it could be an MAF failure include trouble starting, a rough idle and a sudden change in the position of the throttle pedal

Issue with Spark Plugs

Spark Plugs should be replaced following the car’s maintenance schedule set in the manual. If you are not strictly following the manual recommendation a failing spark plug could be the culprit behind a Check Engine Light turning on. So have them checked and replaced as soon as possible.

Issue with the Ignition Coil

The Ignition Coil serves as an induction coil by converting your vehicle’s voltage to the required volts that can trigger the spark plug to ignite the engine’s air-fuel mixture. And when that coil fails the check engine light will come on. If that happens it would be best to have your entire vehicle’s ignition system checked by a service mechanic or auto-electrician.


Diagnosing the Problem


Auto manufacturers have started to standardize their systems with 1996 model-year vehicles under a protocol named OBD-II. In other words, all light-duty vehicles (meaning less than 8,500 pounds) sold since the year 1996 in the United States have on-board diagnostic systems (OBD-II) that can diagnose when your vehicle has certain emission, power-train and other readings that are not within the accepted ranges. 


The OBD II consists of a list of diagnostic trouble codes. The standardization required that all cars provide a universal connector to have access to this information. The connector can usually be found under the steering column. 


Your trusted local mechanic can usually do the diagnosis of the problem but there's another way to preview what the issue might be. Those who would rather do the diagnosis themselves can purchase affordable code readers from an auto parts store or online that connect to the onboard diagnostics (OBD) port and view the corresponding code's meaning on websites such as Engine Light Help. Even Wikipedia has a listing of PID Codes. Some auto parts stores even offer the code readers for free in hopes that you’re a DIY person who would do the repairs yourself and buy the needed auto parts through them. 


Modern systems will be able to display the code through smartphone app, such as: 


  • Bluetooth OBD2 Scan Tool for Android: Once you are able to connect this device through bluetooth, open an app like Torque Pro, OBD Auto Doctor or In Car Doc Pro on your Android phone or tablet and you will then be able to get the codes and reset the check engine light among other things that you will be able to do.




However, more often than not you will still likely still need a professional to do the repair of your vehicle.  Many current vehicle models also have integrated remote diagnostic capabilities, with a convenient capability to report on trouble codes and schedule a service appointment. Auto manufacturers that support it include Ford, Hyundai, Fiat Chrysler and Volvo among others.


In Summary:


Considering the above information, is it safe to keep on driving when the Check Engine Light is on? To recap, the answer is — it depends. Is the Check Engine Light solid or intermittently blinking? Then the answer is yes. Yes, but only for the meantime. And that is if the vehicle is not running strangely. Meaning there’s no strange noise or emission coming out of the car.


You can also do a quick check up to issues that can easily be fixed like a gas cap left loose or left unclosed because it may be the only issue left to be resolved. But if that is not it, you need to understand that today’s automotive computers often try to make up when there’s a problem, so you might not readily see deterioration in the car’s performance, even though your fuel mileage might already be suffering and your vehicle is already emitting unacceptable levels of hydrocarbons and other contaminants. So in any case a Check Engine Light on is never good news and although a solid light means no emergency it is imperative that you have your car checked. 


While it might be tempting to ignore that warning light altogether you are only in the long run hurting your pocket by leaving a minor issue that turns into a major costly problem. 

But again the answer as to the safety of driving becomes definitive in case of a Blinking Light. Once it happens it’s imperative to pull over and have the car checked by a mechanic and that is immediately. A blinking light corresponds to a serious issue. It signifies that there’s an engine misfire that when you keep on driving will result in nothing but further irreversible internal damage (mostly to the expensive catalytic converter) or worse your vehicle might catch a fire. 

The Check Engine Light is there for a reason and that is TO CHECK so once that light comes on do something about it. That is the only way you can ensure you’re always on the safe side.

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