How to Reset Check Engine Light: Very Easy Techniques

Cars give different signs to tell that something is wrong. Many faults in cars could be detected by clicking and ticking sound in the engine or physical damages.  But one very easy way to detect complicated or hidden faults is the check engine light (CEL) illuminating. This, you must reset; else, you will fail your car’s emission test. You don’t want this light on.

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

What Causes Engine Check Light On

Before solving a problem, you must know where the fault is coming from. This is also true with vehicles. Like I stated, the engine check light helps notify the driver of electrical or mechanical faults within the vehicle.

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

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

Check Engine Light

Faulty Oxygen Sensor: The oxygen sensor helps burn up gas 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 lead to the damage of your car’s spark plugs and catalytic converter. So long 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. Else, you won’t pass your car’s emission test.

Faulty Catalytic Converter: Aside from a bad 02 sensor, another thing that can damage your cat is poor vehicle maintenance, such as irregular oil changes and running short distances. This can cause the catalyst to get clogged, then, trigger the engine warning light to come on.

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

Loosed Gas Cap: If your gas cap is loosed, it could be due to a mistake from your end. A loose gas cap will disrupt the system that delivers fuel to your car because it has failed to keep your car under the right pressure. This will result in fuel loss and cause your CEL to come one. 

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 will advise that you should be cautious of this cap. Gasoline is highly explosive, so you don’t want to drive with the gas cap out of place.  Most times, if the gas cap is the problem, the CEL will disappear after you fill 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 quantity of air that enters your car and enables your car to adjust to changes in height. When it is faulty, you will experience tough idling, reduction in gas mileage, and unexpected change in your throttle pedal.

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

Defective Alarm Systems: Car alarms are made to prevent car thefts. But if they don’t work appropriately, it will cause your CEL to turn on. 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 will malfunction and cause your CEL to illuminate or damage other vehicle components.

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

When this coil is faulty, the spark plugs won’t get enough electricity to carry out 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 and cause the CEL to light. 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 Engine Check Light

When your check engine light comes on, ensure you check for possible issues that might prompt 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 by itself 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 how to reset check engine light without a scanner.

Using An OBD 2 Scanner

Most cars are built with the onboard diagnosis computer. This computer tells you when something is wrong with your car. But if, after fixing the problem, your CEL remains, then a code reader will be needed. It is the fastest way to reset your check engine light and 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 check engine light are:

  • SeekoneObd 2 scanner
  • Autophix Obd2 enhanced code reader.
  • Foseal improved version code reader.
  • Schwaben by Foxwell OBD-II code reader.
  • Launch Cr319 obd2 scanner

There are other scan tools, but whichever you choose, ensure it gets the problem fixed.

how to reset check engine light toyota

To reset check engine light with a code reader;

  • Locate your onboard diagnostic connector underneath your car’s steering. Then connect the code reader to it.
  • Turn on the ignition, then, press the red button on the scanner.
  • A set of errors will display, write down these trouble codes, and keep them safe.
  • You can decode those codes using your owner’s manual for your car model.
  • The minute you decode those trouble codes, the problem is detected already.
  • Solve any problem detected yourself or visit a mechanic (the codes you wrote down will be useful to the mechanic and save you time). Change faulty parts when needed.
  • Once done, press the clear or erase button on your scanner to erase the error codes.
  • Once the issue is solved, please turn off your ignition then turn it on again. Then check if the engine check light is still there or has disappeared.
  • Also, check again using your scanner to see if it will give the same error codes or not.

Disconnecting Your Battery

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

  • Switch off your ignition
  • Remove your car’s battery terminals with a socket wrench. Ensure you have your socket set in place in case you need them.
  • Some power will remain in your battery electrical system. Drain out this power by pressing your car’s horn for about 35 seconds.
  • Reconnect your battery cables after about 20 minutes.

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

Turning The Ignition Off And On

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

  • Switch your ignition off and turn it on again.
  • Wait for some time.
  • Repeat this process (off and on your ignition). Four or five times.
  • Drive for a while and check if the check engine light has disappeared.

Let It Go Itself

Driving your car continuously for about three days will clear check engine light. Car works 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 other methods; otherwise, take the car to a proficient mechanic.

Pulling Off The Fuse And Putting Them Back

Another method of eliminating check engine lights is to pull out the engine control unit fuse, then put them back again. 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.


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 of resetting check engine lights. But a high-end scanner is quite expensive and will range from $100 to about a thousand dollars. 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 check engine lights without a scanner.

  • The battery disconnection method.
  • Turn off and on your ignition.
  • Letting it go by itself by running your cars in cycles.
  • Or you can employ the pulling of the fuse and putting back fuse method.

If you started reading from here, please scroll up, as I have already explained these 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 caused the error code occurred many times to turn on the light. This, in most cases, means the problem is not critical, so the code is just stored. In other cases, it could be bad electrical connections or wiring issues. Faulty sensors or stuck valves can also cause it.

In this case, using a scanner or code reader to detect the actual problem will be the best option. The scanner will tell you the problem and 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 to see the steps on how 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 having double 10mm 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 of how to reset the check engine light. One of which is the use of an OBD 2 scanner or code reader. Not only does it reset the check light, but it can also detect what the problem is.

For the other methods, know that several faults in vehicles can trigger the check engine light to come on. So it would help if you first diagnosed what the issue is, 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 couldn’t solve the problem still, you need to seek help from an expert automotive mechanic.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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