Resetting your check engine light is not a difficult process and can be accomplish any number of ways depending on your vehicle’s make. Some cases may take just a push of a button, or the twist of the key or depressing the pedals in the right sequence to reset the check engine light manually.
This process is usually similar for most makes or models, some others like the C5 Corvette or the S80 Volvo require special inputs to get the information you need.
If this fails, you can always source a OBDII scan tool or similar device that’s meant to read codes and clear them. These scan tools are also called diagnostic scanners and can be rented at your local auto parts store.
Disconnecting the battery will always do the trick for clearing trouble codes. Make sure to have the battery disconnected for long enough that the ECU is fully cleared. Check the Disconnect Your Battery Section below for more information.
Knowing how to reset your check engine light is easy, however the real way to reset the check engine light is to resolve the issue with the car. If you need help with your check engine codes or lights on your display, check out our DTC Doctor for more information or one of our partner sites checkenginetroublecode.com.
What to do
Many times these check engine lights can be caused by a very small detail or something that might have changed. Making small mental errors like not inflating your tires completely or not tightening your gas cap can cause the Malfunction Indicator Lamp (MIL) to go on.
Checking these items is quick and easy, but the first order of business should be to get your hands on a scan tool. Connecting this scan tool to your vehicle will allow you to pull the OBDII code out and from it’s structure determine what your problem is.
If a scan tool is not handy or you cannot get to an auto store, visually checking under your hood and around your car can go a long way towards fixing your check engine light. Check for any loose or broken hoses, frayed or damaged wires, check tire pressures and your gas cap to see if it’s tight.
These kinds of small issues can seem minor, but can compound and either cause damage to your engine or vehicle or prevent your vehicle from starting at all.
Checking for Codes
As stated previously, all OBDII vehicles manufactured after 1995 feature a OBDII Communication port that allows you to connect a scan tool to it. This communication port is usually found under your dash or the glovebox, and most scan tools can be rented for a very low cost.
Depending on your year make and model, the communication language your car uses may vary. CAN BUS is a communication protocol that has been a standard for US cars and light trucks since 1996, but was not mandatory until 2008 (2001 for most European vehicles). For more on CANBUS, check out our FAQ page.
If your vehicle is older than a 1995 you will need specific instructions on how to pull the check engine codes from your vehicle. Manufacturers have a preprogrammed function that allows you to read codes by way of flashing the check engine light in diagnostic mode. For more information on OBDI diagnostic modes, check out our DTC Doctor for more information.
Disconnect your Battery
Your vehicle’s Engine Control Unit (ECU) often uses the radio or clock power to keep it’s memory intact, you must disconnect power long enough for the ECU to lose it’s memory. Vehicles from 1996-2004 typically can have the battery disconnected, causing the ECU to clear it’s codes.
Newer cars have even more safeguards to prevent you from clearing the ECU in this manner, so be sure to check your manufacturer process in our FAQ section or simply rent a scan tool.
With the battery disconnected you can aid the ECU in draining it’s memory by trying to turn on your headlights or honk your horn. Most ECU’s have a long lasting capacitor that allows it to retain memory, try to wait as long as you can before reconnecting the battery.
**Tip –If you are disconnecting your battery to clear your check engine light, but do not know what the code is it may be a good idea to scan it first. Many times clearing the code can simply eliminate your issue, if it’s an intermittent problem or one that isn’t that serious.
Unfortunately if your problem is serious or related to emissions, resetting your check engine light by clearing your battery might make it harder to diagnose. Because you are clearing the entire ECU and all the values it’s kept, you will need it to “relearn” the error before you troubleshoot it. Try renting a scan tool and using the freeze frame feature to learn more about your check engine light.
Smogging your Car
If you are on this page and looking for how to reset your check engine light, chances are you need a smog or to pass a smog inspection. Unfortunately for you, disconnecting the battery will not aid you in passing smog. In fact, often times disconnecting the battery can cause more issues as your vehicle may have to undergo a series of drive cycles before its smog ready.
This light can often be confused with the check engine light or cause concern overall, but there’s nothing to fear about the Service or Maintenance Light. These lights are usually preprogrammed by mileage and simply show you it’s time to change your oil or perform regular maintenance.
These lights do not affect your vehicle’s ability to operate, and are merely a reminder albeit an annoying one for most people. Learn how to reset your maintenance light in your Honda Civic, Honda Accord or Toyota Prius by clicking here.
Repair the Car
The last and final step in our how to reset your check engine light article is to repair the existing problem in your car. Clearing your code by way of scan tool or disconnecting the battery only delays the inevitable because you haven’t fixed the problem that caused the check engine light to go off in the first place.
Get yourself a scan tool and find out what code is in your car, refer to our DTC Doctor or one of our partnered websites www.checkenginetroublecode.com for more details on how to reset your check engine light.
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