How To Clear Obd Ii Codes Without A Scanner

How To Reset A Check Engine Light

Our cars are designed in a very sophisticated way. They have many electronic systems, and one part is the car's onboard diagnostic system (OBD system).

Some of the possible malfunctions in your car can be detected either by various inappropriate sounds or by various physical signs. But some faults, that are not easily detectable but do occur in your vehicle are represented bythe check engine light in your car.

In this article, we will go through how you can reset the check engine light.

How to reset check engine light

The easiest way to reset the check engine light is by using an OBD2 scanner. But if you do not have one available, you can often do it without one.
Here are some different ways how you can reset your check engine light:

Total Time: 5 minutes

1. Use an OBD2 Scanner

Reset Engine Light

If you have an OBD2 scanner available, you can reset your Check Engine Light within seconds. To get one, you can check out our other article on thebest OBD2 scanners to buy.
When your check engine light is on, connect the scanner to the OBD connector situated under most car models' steering portion. Then switch on your car's ignition to the ON position. After the connection is established between the computer and the car, press the "read" button on the scanner to search for all the stored trouble codes.
After the scan is complete, note down all error codes diagnosed by the scanner, decode those problems using the user manual of the particular make and model. Once the code is decoded, the problem is detected. Solve that problem; if that part needs to change, then change it or if it needs to calibrate it then carry out the calibration.
Once done, erase the error from the scanner by pressing the "Erase/Clear" button. Once the problem is solved, it is recommended to switch off the ignition, then switch it again, check to see that the engine check light is not on again, and recheck from the scanner whether it is giving the same fault again or not.

2. Battery Disconnection Technique

Disconnect Car Battery

The best way to reset the check engine light without a scan tool is by removing the battery terminal for 30-60 seconds. This will reset the engine control unit in many car models.

First, remove the negative car battery terminal. Then try to drain any available electricity present in the car's capacitor by pressing the horn for around 20-30 seconds or turning on lights. Once the electricity is disconnected, then leave your car for 10-15 mins. After this short time, reconnect the battery terminals, make sure they are well tightened to avoid any possible sparking, and then switch on your car.

If your car gives that same check engine light after restarting, then it means there is some serious problem in your car, or your car stores the codes anyway. In such a case, it is highly recommended to check the codes with a scanner instead because some car models will not reset the codes by removing the power.

3. Turning the Ignition On and Off

Turn Ignition

Switching the ignition on and off is also one method of hard reset without disconnecting batteries. Put the keys in your ignition and turn your ignition on and off consecutively after a second in each step.
Once it is done, see if the engine check light is still coming on or not. If the check light is off, you are ready to go, but if it is still coming on, get ready by reading the codes with a scanner instead.

4. Let it Go Off Itself

Driving Car

Another way to reset the check engine light is to wait and let it go off by itself. It is a straightforward method; you have only to wait and continue driving your car for around three days. Cars' computers work in a continuous cycle and refresh their present state.
Remember that you have to make sure that the problem is gone before using this technique.
For example, if the ECU detects a problem in the oxygen sensor that could occur due to a minor glitch, then it might fix automatically as the ECU will update the sensor's status once the glitch is removed, setting off the check engine light. But if your check light is still on even after three days, then either apply the above-mentioned methods yourself or take your car to a mechanic. Read more about it here: Will the check engine light reset itself?

5. Pulling Off the Fuse and put back

Pull Fuse

One of the possible ways of getting your check engine light to go off is pulling off the engine control unit's fuse and then putting it back again. Although this won't solve the problem in newer cars, it may solve the problem in a little bit older cars, and it is easy to try. Check your repair manual to find the fuse to the engine control unit.

If the Engine Check Light Returns

Once you have your check light disappear, using any of the five above-mentioned methods, then you are ready to go. But if your check light glows again after a few days, it means there is aproblem in your car that needs to get fixed.

It is now time to get your car diagnosed for real with a scanner. Either by buying one yourself orgoing to a workshop that can read the codes in your car.

Can you reset the check engine light without disconnecting the battery?

You can reset the check engine light without disconnecting the battery by using an OBD2 scanner. If you drive long enough after fixing the problem, most car models' check engine light will go away by itself.

How do I reset my check engine light without a scanner?

The best way to reset the check engine light without a scanner is to repair the problem and keep driving for an extended period. In some car models, you can also remove the battery terminals to reset the engine control unit.

How long does it take for the check engine light to reset?

If you are sure you have fixed the problem, it takes around 10-30 successful cycles before the check engine light disappears. One process is one cold-start until the engine is warm.

Will the check engine light go off by itself?

Yes, The check engine light will reset itself after a fixed amount of time if you fixed the problem in most car models. Usually, this is 10-30 cycles. One cycle is from a cold start until the engine is at working temperature. MORE: Will the Check Engine Light Reset Itself?

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Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.