How to reset check engine light once it appears? Many drivers seek a solution to this problem especially if it happens frequently.
Two solutions to this problem: either visit a good and trustworthy mechanic or try to do it by yourself.
Visiting a mechanic is of course the right way to go especially if you suspect and have symptoms of a bigger problem.
But what should you do if everything seems OK with your car, but the check engine light stays on or even worse, goes on and off at certain time intervals? What should you do if the check engine light goes on even after visiting the mechanic and making the repair?
Usually, this means frequent visits to the mechanic which can cost time and money. Not to mention the fact that probably after a few visits, even the mechanic will shrug shoulders and tell you to drive like that. Every visit will cost you time and money as every diagnostic reading and fault code clearing is charged (in most cases).
So, you can easily end up with lost time, money, and an unsolved problem.
On the other hand, you can try to reset the check engine light on your own.
In this article, we’ll focus exactly on that and on some of the most common DIY ways to make a reset.
You can certainly do this on your own. The possibility of damage is minimal and even if you don’t succeed, you can always drive the car back to the mechanic.
All you’ll need is some goodwill, basic car knowledge, and some tools.
RESET CHECK ENGINE LIGHT IF THE PROBLEM IS SOLVED
Before we start, I’d like to emphasize one thing almost all people tend to do.
That is to reset the check engine light and ignore the actual problem.
Have always in mind that the check engine light goes on for a reason.
(If you want to know more about these reasons click here for a separate article on that topic or watch a video on our YouTube channel.)
The ECU (Engine Control Unit) constantly monitors most of the systems in the car. One of its main tasks is to tell you that there’s an error and signalize (among others) with the check engine light.
Sometimes it may be a minor twitch in one of the systems but also can be a serious fault that needs to be solved right away.
So, if the check engine light appears rarely, go ahead and do the reset procedure. Get the fault code and try to inspect the problem and possible causes.
Monitor if it appears after that and at what interval. If it’s a glitch in the system, then you’ve solved the problem and the check engine light won’t appear. I’ve had one of these situations myself, if you’re interested in how I solved the problem click here for a separate article on that topic or watch the video.
If there is a serious malfunction, then a check engine light reset will not help and the light will continue to pop up.
On most cars, if the check engine light is constantly glowing, then the problem is the more minor meaning you can probably continue driving.
If it starts to blink, then the problem is worse. In that case best stop driving the car.
ON WHAT CARS SHOULD YOU ATTEMPT TO RESET THE CHECK ENGINE LIGHT?
Another point which I would like to make before you start to reset the check engine light.
Today’s cars are becoming more and more complicated regarding electronics.
They are, more or less becoming computers on wheels. This has its advantages, but from the maintenance point of view, it’s simply getting harder.
Upper-class cars (premium, luxury, performance cars, etc) tend to have complicated electronic systems that are intertwined in ways that can cause unpredictable side effects. They simply have more electronics on them.
Middle and lower class cars tend to have less complicated electric and electronic layout making them more suitable to reset check engine light on your own.
The main point here: if you drive a premium car with a more complicated electronic layout (read lots of gadgets multiple ECU-s or else), best don’t try this.
Due to the complicated nature of the installation, there may be unpredictable side effects that will cause problems. Perhaps you’ll reset the check engine light, but you’ll damage something else.
Also, these kinds of cars usually demand specific diagnostic tools that are expensive and complicated.
So, if you’re driving a “spaceship”, best leave this to professionals.
If you’re driving a medium or lower class car (read less complicated), go right ahead.
WHAT TOOLS WILL YOU NEED TO RESET THE CHECK ENGINE LIGHT?
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OBD II SCANNER
This is the proper way to go. OBD II scanners have connectors that access the ECU unit on the car and make a readout of the faults. Basic ones can read fault codes and clear them.
If you don’t have one, you can buy a good OBD II scanner for about 30 Euros (depending on type, function and you’re market). Of course, you have the professional ones, but they are both expensive and more complicated to use.
In recent times, wireless OBD II scan tools have appeared. You have an OBD II connector that connects to a smartphone via wireless and does a scan and clears codes. Haven’t tried these yet, but I think certainly worth the try.
Since making a check engine light reset is not a job made frequently, you can also consider borrowing or renting one to solve your problem.
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LAPTOP WITH OBD II CONNECTION CABLE
Today almost everyone has a laptop. If you do, you can utilize it to reset the check engine light.
What you’ll need, besides a laptop, is an OBD II scan cable and a program that suits your car model.
Cables and programs are sold in sets or can be bought separately.
Computer programs for scanning can also be found online. I would recommend specialized forums for this. These are maybe the best places as people also talk about their experiences using this software.
Have in mind that, in most cases, these programs have only the basic functions (reading and clearing codes).
For more professional programs and with more options, you’ll have to pay some money.
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RATCHET WITH PROPER SOCKETS OR A SIMPLE WRENCH
After all of these electronic gizmos, back to some real tools.
Nothing special needed, you can use old school wrenches. The sizes you’ll need (in millimeters) will be mostly 8 mm, 10 mm, and 13 mm. Of course, there are exceptions, but the mentioned ones are used on the majority of cars.
You can also use a ratchet and socket, but they are a bit unwieldy as you may have problems reaching the battery terminal connectors. Use the same size of sockets mentioned with the classic wrenches.
RESET CHECK ENGINE LIGHT BY DISCONNECTING THE CAR BATTERY
This method is by far the most popular and widespread.
Two main reasons: it’s very simple and you need only basic tools.
No OBD II scanner, no laptop, cables, etc. just a wrench or ratchet and taking off one or both battery terminal connectors.
Simple as that.
By disconnecting the battery, you’re cutting off the power supply to the ECU causing it to make a full reset. Much like taking batteries out of a watch. The basic principle is the same.
Before you start the procedure make sure to take some safety precautions:
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Leave the driver’s side door open or lower the window. If something happens you can gain access to the car even when you disconnect the car battery. Also, if you have a coded car stereo, make sure that you have the code at hand as it needs to be entered once the battery is reconnected.
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Watch that you don’t accidentally short-circuit the battery terminals with a wrench. This is a common mishap for inexperienced people. This usually happens if you have a longer classic wrench that can bridge the two battery terminal connectors. If you’re working with this kind of wrench, be careful in what direction you’re unscrewing. Either this or use a ratchet or wrench that has rubber or plastic protection on one side.
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Take the keys out of the ignition, best take them out of the car.
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If you drive a car with manual transmission (stick shift), put the car in neutral and pull the hand brake. For automatic transmissions, put the car in “P” and pull the hand brake.
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If the car battery is not in plain sight once you’ve raised the hood, you’ll find it in a plastic casing. It usually has markings on it and cables coming out. You should be able to recognize it easily.
This procedure can be done in two ways:
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Taking one of the battery terminal connectors off (namely the minus one)
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Taking both of the connectors off (minus and then plus).
Both have the same effect although the second one, in my opinion, is better. We’ll go through both.
1.Taking off the minus battery terminal connector.
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You’ll find either a screw or a nut on the battery connector. Loosen it with a wrench or ratchet. If the connector hasn’t been removed for a long time you might have to give it a budge from left to write. You can use a flat-head screwdriver to loosen the grip of the connector. If you have a clamp system with no screws or nuts, just unbuckle the clamp.
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Put the connector and minus cable aside at a safe distance so it doesn’t spring and accidentally make a connection.
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Leave it like that for about half an hour.
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In the meantime press the horn on the steering wheel and hold it for 30 seconds. This is for draining any remaining electricity in the system.
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Return the battery connector on the terminal and tighten. Tighten slightly so you don’t damage the connector.
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Start the car. If everything is OK, the check engine warning light should go away. Since this is a reset, best let the car idle for some time so the ECU can collect new data.
2.Take of both of the battery terminal connectors
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Take off the minus (“-“) battery terminal connector first. After that remove the plus one (“+”). Go in this order as you’ll reduce the possibility of accidentally causing a short-circuit by connecting the plus terminal to the car body or engine with the wrench. You’ll find either a screw or a nut. Loosen it with a wrench or ratchet. If the connector hasn’t been removed for a long time you might have to give it a budge from left to write. You can use a flat-head screwdriver to loosen the grip of the connector.
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Put both of the cables aside at a safe distance so they don’t spring and accidentally connect to the battery terminal again.
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Connect the plus and minus cable while they are disconnected from the battery. Just put them together with your hands and hold them like that for about 30 seconds. If they are too far apart, use a jump-start cable to make the connection. This is another way of draining any remaining electricity in the system.
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Leave the cables disconnected for about half an hour.
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Return the connectors onto the battery terminals and tighten them. First plus (“+”) then minus (“-“) Tighten slightly so you don’t damage the connectors.
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Start the car. If everything is OK, the check engine light warning should go away. Since this is a reset, best let the car idle for some time so the ECU can collect new data.
So, as you can conclude a very simple procedure. Again, if the check engine light went on because of a temporary glitch, this method should make it go away. If it returns, then make a thorough check of what’s wrong.
While waiting for the ECU to reset, you can inspect both the battery terminal connectors and terminals.
Check that they are clean and corrosion-free. Good contact is key to the proper function of the electric and electronic systems in your car.
You can use sandpaper, a small file, or a cleaning solvent for this purpose.
HOW TO RESET CHECK ENGINE LIGHT WITH AN OBD II SCAN TOOL?
As mentioned the OBD II scan tool is essentially a tool that reads and clears fault codes.
You’ll probably be using the basic one which has an old school type screen (like a digital watch) and a set of buttons for navigating the menu. These are the most widespread and least expensive.
Of course, there are ones with LCD displays and more functions, but these tend to be more expensive and are usually meant for professional use.
OBD II scanners work on a basic “YES” or “NO” principle and the navigation is mostly up, down left, or right through the menu. If you’ve played Tetris, you’ll know how to do this, trust me.
Here we’ll state a basic principle, it varies depending on the type of scanner but you should be able to get the idea.
1. Find the OBD II connector
These connectors are mostly hidden behind a plastic hatch or less visible places (like above the foot pedals).
Each car model has a location of its own. I would recommend Google it to save yourself some time and wandering around. Believe me; some manufacturers have made it like seeking lost treasure.
Most common places would be under or around the steering wheel column, above the foot pedals, or inside the fuse box.
2. Connect the OBD II scan tool
This connection is universal, so any OBD II tool should fit. Connectors are easily recognizable, something like you would find on a computer.
Before you press the connector in, make sure it fits properly so you don’t damage the pins and connectors on both the car and the scan tool.
3. Turn the ignition key
DON’T CRANK THE CAR!!! Just turn the ignition so the lights on the dashboard go on. This gives power to the ECU making it able to communicate to the OBD II scan tool.
4. Let the scan tool work (connecting and scanning).
You’ll see on the display a message where the scan tool is reporting that it’s establishing communication with the car ECU. If everything is OK, it will start to scan. This may take a few minutes. Let it be and don’t interrupt.
If it stalls, check the tool-to-car connection once again.
5. Read the error codes
Once the scanning is finished, the error code(s) will appear. Error codes are expressed in letters and numbers (like P0171, P0162, etc) and in some diagnostics, a few words of explanation are added.
6. Find the meaning of the error code
Now, this part is most important, as you are obtaining knowledge of what’s wrong and how serious it is.
Best Google the error code and find out what’s wrong. You can also use manuals or literature if you have them.
The advantage of internet searches is that you get a more broad span of information (what, where, and perhaps how to solve the problem, experiences, etc).
My advice on this part: if you conclude that the malfunction is more serious best tend to it right away. Trying to reset the check engine light will, in this case, be only a waste of time. It will light up again the moment you re-start the car.
If it’s temporary, then you’ll probably be able to solve the problem.
Maybe the best example regarding when you should reset the check engine light is a faulty lambda sensor error code.
It may be caused by low-quality fuel, excessive air in the gas tank, or else which are basically one-time mishaps.
When you change the gas station or vent the gas tank via the gas tank cap the problems will be gone.
In this situation, a DIY reset is very welcome.
7. Reset the check engine light
In the menu of the OBD II scan tool, you’ll find menus that will let you access reset functions.
Most OBD II tools work on the same principle, so just use the navigation buttons and work it out. Usually, it’s not complicated.
Press the reset button and you’re finished.
8. Disconnect the OBD II scan tool and turn off the ignition.
9. Start the car. If everything is OK, the check engine light warning should go away. Since this is a reset, best let the car idle for some time so the ECU can collect new data.
If everything is OK, the check engine light should go off and stay that way.
HOW TO RESET CHECK ENGINE LIGHT WITH A LAPTOP AND AN OBD II SCAN CABLE?
Here, it’s the same principle as with the OBD II scan tool. Instead of the scan tool, you’ll be scanning with a laptop.
As mentioned, you’ll need the software program for scanning and the OBD II cable.
Before you start, install the program on the laptop and get acquainted with it. It’s installed like every other program, nothing special. This will all make work easier later in the process.
Some versions have pre-installed scanning software in a device on the OBD II cable, so no installation is needed.
1. Find the OBD II connector
These connectors are mostly hidden behind a plastic hatch or less visible places (like above the pedals).
Each car model has a location of its own. I would recommend Google it to save yourself some time and wandering around.
Most common places would be under or around the steering wheel column, above the foot pedals, or the fuse box.
2. Start the program on the laptop
As with every other program, just click the icon on the screen.
3. Connect the OBD II cable to the USB connection on the laptop
4.Now connect the OBD II connector to the port on the car
Before you press the connector in, make sure it fits properly so you don’t damage the pins and connectors both on the car and the scan tool.
This connection is universal, so the OBD II cable should fit. Connectors are easily recognizable, something like you would find on a computer.
5. Turn the ignition key
DON’T CRANK THE CAR!!! Just turn the ignition so the lights on the dashboard go on. This gives power to the ECU making it able to communicate with the scanning program.
6. Press the “scan” button and let the program scan for errors
On almost every program you’ll find a scan button. Press it and let the program do its thing.
It should report a list of errors if there are any. Similar to the OBD II scan tool, the codes will be expressed in numbers and letters.
A good thing here is that on these programs you usually get a more thorough explanation of the fault unlike with the OBD II scan tool.
You can even save a report for later or print it out.
7. Find the meaning of the error code
Now, this part is most important, as you are obtaining the knowledge of what’s wrong and how serious it is.
Best Google the error code and find out what’s wrong. If you have manuals or literature, even better. The advantage of internet searches is that you get a more broad span of information (what, where, and perhaps how to solve the problem, experiences, etc).
If the problem is serious, tend to it right away. If it’s temporary then the check engine light reset will be very useful.
8. Reset the check engine light
In the menu of the scanning program, you’ll find an option for resetting. Just use the reset button and your good to go.
9. Disconnect the OBD II cable from the carport
10. Start the car. If everything is OK, the check engine light warning should go away. Since this is a reset, best let the car idle for some time so the ECU can collect new data.
If everything is OK, the check engine light should go off and stay that way.
LET THE CAR ECU AUTOMATICALLY RESET CHECK ENGINE LIGHT
This is the easiest method as all you have to do is wait for the reset to happen by itself.
Once the repair is done, the ECU should get proper readings thus turning off the check engine light (on most cars, this is the case).
People are not aware that the ECU needs time to process this information. While that’s happening, the check engine light stays on although everything is OK.
Have in mind that the classic ECU is a primitive type of computer after all and needs some extra time for processing.
So, if you’ve done a repair on your own and you’re certain that you’ve solved the problem, you can let the check engine light stay on for a couple of drives.
Maybe better than going through extra work with an OBD tool (if you have one) or disconnecting the battery.
If everything is OK, it will turn off in a short period of time (something like three or four drives).
If you’ve driven the car to the mechanic, you won’t have these problems as they will make the reset once they’ve finished the repair.
FIND AND PULL OUT THE ECU FUSE
On all cars, you’ll find a fuse for the ECU unit.
(If you want to learn how to replace a blown car fuse, click here for a separate article on that topic. You also have a video tutorial on our website or on our YouTube channel.)
What you’re essentially doing is cutting off the power supply to the ECU. Once you’ve pulled out the fuse, the power supply is cut.
In essence, you’re doing the same thing as with disconnecting the battery only on a smaller scale and only for the ECU line, not the whole car.
The procedure is very simple:
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Turn on the ignition (don’t crank)
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Find the fuse for the ECU. It will have a recognizable icon, mostly looks like the check engine light.
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Pull out the fuse. Wait for a few minutes.
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Turn the ignition off and then return the fuse in place.
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Turn the ignition on and start the car. Here it would also be good to let the car idle for some time so the ECU can collect new data.
I don’t recommend this procedure on more high-tech cars, As mentioned these have more complicated electronic components and cutting of the ECU power supply may have side-effects on other systems causing even more problems.
On middle and lower class cars, it’s worth the try.
Not my favorite method to be honest, as there is always the distant possibility of causing other damage.
TURN THE IGNITION KEY FEW TIMES IN A ROW
Try this method although I don’t think it will help that much.
Basically relies on the principle that through frequent turning on and off of the power supply to the ECU, a reset of the check engine light will be induced.
Much like the method of waiting for the check engine light to go off by itself but minus the waiting.
If the ignition key causes you problems and won’t turn, read how to fix it or watch a video tutorial.
I’ve tried this method to reset the check engine light and to be honest, it didn’t work for me
This doesn’t mean it won’t for you. Worth the try since it’s free doesn’t take much time and no work is involved.
