How to Reset Check Engine Light: Very Easy Techniques

Cars give various signs that something is wrong. Many faults in cars can be detected by clicking or ticking sounds in the engine, or by physical damage.  But one very easy way to detect complicated or hidden faults is the check engine light (CEL) illuminating. You must reset this; otherwise, you will fail your car’s emissions test. You don’t want this light on.

Before I describe to you how to reset the check engine light, ensure you have addressed the issue(s) causing it to illuminate. This will lead us to possible causes of the check engine light being on.

What Causes the Engine Check Light to Turn On

Before solving a problem, you must know where the fault originates. This is also true with vehicles. As I stated, the engine check light alerts the driver to electrical or mechanical faults in the vehicle.

In some cases, it could be an error from your engine. Before carrying out other checks, ensure there are no slip-ups in your engine.

If your engine is okay, then you might want to have other components checked. Possible causes of the engine check light are:

Faulty Oxygen Sensor: The oxygen sensor monitors and adjusts the air-fuel mixture in your car’s engine. The amount of oxygen in your exhaust that is left unburnt is measured by this component. When this component is faulty, your car will burn more fuel.

Excessive fuel burning will damage your car’s spark plugs and catalytic converter. As long as the oxygen sensor isn’t working as it should, your engine check light will illuminate.  You may need to visit an expert mechanic to have it replaced. Otherwise, you won’t pass your car’s emission test.

Faulty Catalytic Converter: Aside from a bad O2 sensor, another thing that can damage your cat is poor vehicle maintenance, such as irregular oil changes and short trips. This can cause the catalyst to clog, which in turn triggers the engine warning light.

Vacuum Leakage: One function of the vacuum system is to reduce toxic emissions. Once there is a leak, your car will spurt or settle at an unusually high PRM. The leak is usually caused by damaged fittings, loose connections, or a dry vacuum hose.

Loose Gas Cap: If your gas cap is loose, it could be due to a mistake on your end. A loose gas cap will disrupt the system that delivers fuel to your car because it fails to maintain the proper pressure. This will result in fuel loss and trigger your CEL. 

It may be that you forgot to replace the gas cap or tighten it properly after fueling with gasoline. This can happen to anyone, especially when in haste to go out.

But I advise that you be cautious about this cap. Gasoline is highly explosive, so you don’t want to drive with the gas cap out of place.  Most of the time, if the gas cap is the problem, the CEL will disappear after you fill up and tighten the cap properly.

So ensure you replace or tighten the gas cap properly after fueling with gasoline. If the gas cap is faulty, please have it replaced.

Mass Airflow Sensor Failure: This component measures the amount of air entering your car and enables it to adjust to changes in altitude. When it is faulty, you will experience rough idling, reduced gas mileage, and an unexpected change in the feel of your throttle pedal.

Faulty Thermostat: The thermostat controls the flow of coolant to your engine. When it is bad, it triggers your CEL.

Defective Alarm Systems: Car alarms are made to prevent car thefts. But if they don’t work properly, it will trigger your CEL. Not all alarms can work effectively, so ensure you get a quality one that can prevent theft.

Stay away from cheap alarms. You don’t want an alarm that malfunctions and causes your CEL to illuminate or damages other vehicle components.

Faulty Ignition Coil and Spark Plugs: Your vehicle’s spark plugs get power from the ignition coil, which makes them radiate sparks. The spark, in turn, burns the air-fuel mixture in your car’s cylinder.

When this coil is faulty, the spark plugs won’t receive enough voltage to perform their function. Thus, causing the engine check light to come on.

In other cases, if the coil is good but the spark plugs are old or worn, your engine will misfire, causing the CEL to light up. Therefore, ensure you replace bad engine coils or old/worn-out spark plugs.

Dead Battery: Your battery should last at least 5 to 7 years. If it has expired, it may not charge well and cause your engine light to come on. Again, depending on how you use it, it might get worn out before then. So if it doesn’t charge and also gives you issues, then you will need to replace it.

How To Reset the Engine Check Light

When your check engine light comes on, check for possible issues that might have triggered it. You can look up reasons why your check engine light is on.

After detecting and fixing the problem, the check engine light should reset on its own after about 20 to 30 cycles. This might be equivalent to three (3) days.  (A car’s cycle starts your car, drive until it warms up, then put it off.) So, 10 or 30 cycles will mean repeating this process 10 or 30 times.

But if after doing these, the light still does not disappear, you will need to reset it using a code reader or scanner. But if you don’t have one, the other methods will walk you through resetting the check engine light without a scanner.

Using An OBD 2 Scanner

Most cars are built with an onboard diagnostic computer. This computer tells you when something is wrong with your car. But if your CEL remains after fixing the problem, you will need a code reader. It is the fastest way to reset your check engine light, and it will work better for cars produced before 1996

This scanner helps read and delete trouble codes, so you may not need to visit a mechanic every time your car(s) have issues. Because it will not only detect the problem but also show you how you can fix it.  Good examples of scan tools that help turn off the check engine light are:

There are other scanning tools, but whichever you choose, ensure it fixes the problem.

To reset the check engine light with a code reader;

Disconnecting Your Battery

This is a fast and easy way to reset the check engine light without using a scanner. This method will work for some car models but won’t for others. However, to do this:

This should clear the check engine light. But if it doesn’t, it may be that other issues remain unresolved. You can have the car checked by an expert mechanic.

Turning The Ignition Off And On

This is another easy way to turn off the check engine light. To do this,

Let It Go Itself

Driving your car continuously for about three days will clear the check engine light. Cars work in cycles. So after finishing about 10 to 30 cycles, which should take about three days, the light should disappear. As I stated earlier, a cycle is turning on your car; drive until it warms up, then turn it off again.

Remember, for this method to work, you must have fixed the problem that prompted the light to come on. If this method doesn’t work, try another method; otherwise, take the car to a qualified mechanic.

Pulling Off The Fuse And Putting Them Back

Another method for clearing the check engine light is to pull out the engine control unit fuse, then put it back in. It is fast and very easy to carry out.

However, this method will likely not work for recently manufactured vehicles. But it may work well for older cars.

FAQ

Q: How Do I Clear My Check Engine Light Without A Scanner?

First, ensure you have fixed the problem. The scanner is the most efficient and modern way to reset the check engine light. But a high-end scanner is quite expensive and can range from $100 to about $1,000. In reality, not everyone can afford it. If you can borrow from a friend or hire one, fine. But in its absence, other methods can be employed.

The following highlights how to clear the check engine lights without a scanner.

If you started reading here, please scroll up; I have already explained the methods listed here.

Q: Can You Reset Check Engine Light Without Disconnecting The Battery?

There are many methods you can use to reset CEL. So yes, you can reset your check engine light without disconnecting the battery. You can do it using a code reader or scanner. In some cases, the light will disappear itself after driving your car for a while. But remember, you must have fixed whatever problem is wrong with your car.

Q: How Long Does It Take For Check Engine Light To Reset?

After fixing the problems, it should take about 10 to 30 cycles before the light disappears. Remember, a complete cycle is turning on your engine, drive until it’s warm, then, put it off again.

Q: Why Is My Check Engine Light Off, But Code Still There?

If the light is off but the code still appears, it may be due to several reasons. The fault that triggered the error code occurred repeatedly when trying to turn on the light. In most cases, this means the problem is not critical, so the code is just stored. In other cases, it could be due to poor electrical connections or wiring issues. Faulty sensors or stuck valves can also cause it.

In this case, using a scanner or code reader to identify the actual problem is the best option. The scanner will tell you the problem and the things you need to get fixed. But if you can not decode the fault code and fix the problem, reach out to a mechanic.

Q: How Do I Permanently Delete Engine Codes

To permanently delete engine codes, you will need an OBD 2 scanner or code reader. Would you mind looking up the steps to erase engine codes using the scanner? Please, do not clear trouble codes without deducing where the error codes came from and fixing them.

Q: What Fuse Controls The Check Engine Light?

The fuse that controls the check engine light is a small yellow box with two 10 mm fuses. This double fuse is placed on the fuse box located under the dash with a reading ‘ ROOM/PLAFON

Final Thoughts

By now, you must have learned different methods for resetting the check engine light. One of which is using an OBD-II scanner or code reader. Not only does it reset the check light, but it can also detect the problem.

For the other methods, know that several vehicle faults can trigger the check engine light. So it would help if you first diagnosed the issue, then fixed it before you reset the CEL. If you do not reset this light, you will fail your car’s emission test.

We’ve tried to show you everything simply. All these DIY procedures are pretty easy to perform and deal with. However, things may go wrong sometimes. If you’ve gone through all these steps and you still couldn’t solve the problem, you need to seek help from an expert automotive mechanic.