Check Engine FAQs and Troubleshooting Guide

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In most instances, the check engine light is considered the first sign of a slowly dying car, especially when it stays on even after checking the engine and finding no visible issue. Or keeps blinking furiously even after ensuring the engine is working fine.

This may cause you to panic as you may think that something is seriously wrong with your car. While this may be the case from time to time, it is not always the case. This guide seeks to educate you on the issues pertaining to the check engine light and how to resolve them.

What should I do when the check engine light comes on?

The check engine light usually blinks or emits a solid light depending on the underlying issue. The blinking light may be red, yellow, or orange, depending on the car type. A yellow check engine light indicates problem investigation is required in some cars, and a red one means stop right now.

Blinking light

The flashing light is meant to catch your attention and typically indicates a severe engine misfire. This can be due to unburnt fuel is being dumped into the exhaust system, which can damage the catalytic converter.; which is quite expensive to repair.

In this case, reducing the car power and having the car or truck looked at as soon as possible is advised. Some cars’ computer control units may reduce the power on their own to try and limit damage risk to the vehicle.

Solid light

If the check engine light is steady, the issue at hand is not an emergency and can be fixed when you are not in transit. But it is still essential to schedule an appointment with your mechanic as soon as you can.

Check this too: Can You Pass Emissions Check With Engine Light On?

Any unattended engine problem can cause permanent damage not only to the engine but to other parts of your car as well. It may also lead to excessive fuel consumption or reduced engine performance.

Troubleshooting check engine light

in some cases, the blinking light may be caused by a loose gas cap. To eliminate pesky reasons and an expensive trip to your mechanic for no reason, perform the following checks to figure out the cause of the check engine light illumination;

  • Check your dashboard gauges and lights for indications of low oil pressure or overheating. You may have to pull over and shut off the engine as soon as possible.
  • Try tightening your gas cap and see if the light will reset. Though some cars have a different, lose gas cap indicator.
  • Use built-in diagnostic services, if available. Newer car models have integrated remote diagnostic capabilities, producing trouble codes and scheduling a service appointment. These include. Fiat Chrysler, Ford, Hyundai, Jaguar/Land Rover, and Volvo.
  • Lastly, reduce speed and load to minimize engine overload. In this instance, a vital sign of a struggling engine would be loss of power. Also, remove any towing gear or stop towing cargo until your car is fixed.

How do you clear engine codes without a scanner?

In most intelligent gadgets, error codes may linger even after the underlying issue is resolved. The same case applies to modern cars. Once you have repaired your vehicle, the engine code may remain for no apparent reason. Here is an easy process to reset trouble codes without using a scanner;

  • Engage the parking brake and pop open the hood after ensuring your car is level.
  • Remove the negative (-) black cable from the battery. You can use a wrench to loosen the clamps on the battery terminals.
  • Then remove the positive (+) red cable from the battery. The negative and positive cables should not touch. This can lead to electrocution or even an explosion.
  • Cycle the engine 3 to 5 times by turning it ON and OFF.
  • Then press on the horn button in the steering wheel and hold it down for 30-60 seconds to drain out all the stored power in the ECU capacitor.
  • Then wait 10 to 15 minutes before reconnecting the battery.
  • Reconnect the battery cables starting with the red positive terminal and then the black negative terminal. Ensure you tighten the clamps properly.
  • Then turn on the car and check to see if the check engine light is still on.
  • You can also try pulling off the fuse from the engine control’s unit and putting it back to reset the computer.

How do to clear engine codes with an OBD scanner?

Here are steps necessary to clear engine codes with an OBD scanner;

  1. Plug the reader into the OBD port of your vehicle. It is located on the underside of the dash area just above the footwell. You may have to remove the door from the fuse box to access the port in some cars.
  2. Press the “enter” button to turn it on.
  3. The device will scan your engine for any error codes and display any error codes it finds. Refer to the code reader’s manual to see if the car has any issues. If not, you can proceed with the engine codes reset.
  4. Press the “scroll” button to find the option to erase the code.
  5. Press enter while on this option to erase the fault code and reset the check engine light.

Note: Resetting the engine code automatically resets the check engine light as the engine error code is the light illumination source.

Will the check engine light reset itself?

Yes. If the issue is resolved, the engine light can reset itself. But this may not happen immediately. You may need to drive around a couple of times before this happens. Some cars check engine resets in 10-30 cycles.

A cycle being the entire cold engine to powering mode when turned on. In some cars, the check engine light is programmed to reset after a preset amount of time once the issue is resolved.

Where can I get a free check engine light diagnosis (in the US)?

Here is a list of places you can get your car’s check engine diagnosed for free;

  1. Your local car dealership if your car is still under warranty.
  2. Your local auto parts store, but you need to verify if they will do it for free before visiting.
  3. Your local workshop. They need to fix the issue; hence they have to check the code.

Can I reset the check engine light myself?

Yes. If the underlying issues are minor or if you follow the code clearing steps discussed above.

Can the check engine light come on for no reason?

No. If the check engine light is on, it is more than likely that something is amiss. If you perform a self-diagnostic and cannot figure out what is wrong with the car, have a professional perform an error code check or troubleshoot the issues.

Why is the check engine on, but the car runs fine?

This happens when the underlying issue is minor such as a loose gas cap. It does not necessarily affect the performance of the car. But it still needs to be addressed in this case to avoid fuel contamination.

How long will it take the check engine light to go off after a badly closed gas cap?

After you tighten the gas cap, the check engine light should go off after a few minutes of driving. If your check engine light goes off once you tighten the gas cap, then the cause of the light is the loose gas cap. You can replace it to avoid having to keep tightening it.

What does it mean when your check engine light flashes then stop?

This means that your car’s engines are misfiring and should be fixed immediately. This can be due to damaged or worn-out spark plugs or other issues. This flashing is critical and should be resolved immediately to avoid causing further damage to the car.

Can I drive my car with the check engine light flashing?

Yes. But that does not mean you should. An engine misfire can damage the catalytic converter in your car. Repairing the damage will end up costing you an arm and a leg. As such, it is best to get towed as soon as you check engine light starts flashing.

How long can you drive with the check engine light on?

In all practicality, unless you have a flashing check engine light, you can get away with driving to your local car shop to get your car fixed instead of paying to get it towed. Or you can also drive it home or to a safe spot where you can self-diagnose the cause of the flashing light.

However, the shorter the distance, the better as the underlying issue may be problematic and lead to more car problems if left unattended. According to statistics, people drive their cars an average of nine days before taking their car to the shop to be fixed.

While the steady light is indicative of a less urgent issue, you should never ignore it. If left unchecked, the problem can cause progressive damage to your car. Causing the cost of repair to spiral in the long run. Despite not noticing a change in car performance, it is still better to be safe than sorry.

Note: If the issue is already resolved, but the light keeps flashing, you can reset the light or let it reset on its own. In some cases, you may need to use an OBD scanner to do so.

What to do if the check engine light comes back on after leaving the mechanic

This can be pretty frustrating and stressful. The computer in your vehicle may not have recognized the problem resolution that the issue has been resolved. Fortunately, you can easily amend this. If you have just had your car fixed and you check engine light is still flashing, there are several things you can do to reset the light. You will also need to have the mechanic inspect the car once more to ensure it is absolutely fine.

Once you are sure the car does not have any issues, try one of these methods to resolve the persistent check engine light issues;

  • Drive around as it may take several drive cycles for the light to reset itself. This can take up to three days. If the light is still on after, the car is not fixed and should be rechecked.
  • Turn the car ON and OFF three times to reset the light. This is an automatic reset program for some vehicles. Insert your car key into the ignition and turn the car on for about one second. Then turn it off for about a second. Repeat this two more times and drive the vehicle as usual.
  • Disconnect the car’s positive power cable from the battery for at least 15 minutes to drain power from the car’s control unit. Then perform the automatic reset program mentioned above. This will reset the car’s computer system and ultimately reset the check engine light. Then reconnect the cable and turn the car on.
  • As a last resort, you can use an OBD Code Reader to analyze and clear engine codes.

Most common check engine light causes

Some check engine light causes are flimsy, while some are incredibly problematic. Here are the leading causes of the check engine light turning on;

  1. Loose gas cap

You can resolve this by simply tightening the cap. The gas cap helps maintain pressure in the tank, prevent the release of fumes from the gas tank, and keep the gas from evaporating.

  1. Worn out or damaged spark plugs

Damaged spark plugs prevent the engine from firing correctly. Which in turn leads to the release of unburnt fuel. This can be potentially catastrophic. And it can also lead to the destruction of other car components. It may also lead to poor car performance and higher gas mileage.

  1. Damaged or clogged catalytic converter

The catalytic converter converts dangerous carbon monoxide into carbon dioxide. It is vital as it not only protects the environment and your health. And without a properly functioning catalytic converter, your car will not pass the vehicle emissions test required for registering with your state department of transportation.

A damaged catalytic converter or a clogged catalytic converter lowers your car’s fuel efficiency and causes your vehicle to overheat.

  1. Overheating

This issue will be accompanied by other problems such as smoke coming from the car hood or the temperature gauge going berserk. You should always address these issues immediately. Turn on the car heater to help dissipate the heat from the engine if this does not work. Pullover and have your car towed.

  1. Faulty oxygen sensor

The oxygen sensor monitors the unburnt oxygen coming out of your car’s exhaust. This helps your vehicle accurately monitor fuel consumption. A faulty oxygen sensor can compromise fuel efficiency and potentially damage your car’s spark plugs and catalytic converter.

Check this too: How To Bypass Catalytic Converter Check Engine Light

  1. Faulty mass airflow sensor

The mass airflow sensor measures the air entering your car engine and instructs your car’s computer on how much fuel it needs. A malfunctioning mass airflow affects fuel release, which in turn affects engine performance and fuel economy. If left unattended, this can damage spark plugs, the oxygen sensor, and the catalytic converter.

  1. Faulty diagnostics program

The car’s internal diagnostic mechanism could be damaged, causing it to detect a problem that doesn’t exist. This can result from loose system wires, which in turn creates a false positive in the diagnostic system.