An illuminated CEL or malfunction indicator light (MIL) warns you when your vehicle’s onboard diagnostic system detects a possible issue. However, there are scenarios where the light won’t turn off even after resolving the issue. Seeing the illuminated CEL can be annoying, especially since you know you’ve already fixed the problem.
The most common way to reset the MIL light is to reset the vehicle’s computer by disconnecting the battery and reconnecting it after 30 to 60 seconds. This is done by unscrewing the bolts on the battery’s negative terminals and disconnecting the cable.
The problem with this approach, however, is that you have no idea what code or how many codes there were before you erased them and you‘ll have to reset your radio and clock, among others, which is not ideal. If you do know what the codes are, that means you have a scan tool and you don’t need to erase the codes by disconnecting the battery.
Sometimes, replacing a part (like a faulty IAC valve) will require the PCM/ECM’s adaptive tables to be emptied so it can start fresh and relearn its optimum numbers for idle speed with the new IAC; simply clearing the codes won’t do that.
Having said that, here are some tips for resetting the check engine light:
You can use a scan tool to remove the CEL by clearing or erasing the logged trouble codes. This process involves plugging the scan tool into your vehicle’s data link connector (DLC), which is the OBD port where you connect the scan tool. It’s usually located under the steering column. This port isn’t readily apparent and you may or may not need to remove a plastic cover. You can refer to your vehicle owner’s manual to find the DLC.
Once the tool is plugged in, retrieve the codes. There are “on demand” codes and there are “continuous memory” codes. An on demand code is a problem that is present at the time of testing. A continuous memory code is something the PCM/ECM has noticed on a previous drive cycle and may not be something that is happening now.
If the problem doesn’t reoccur within a couple of complete drive cycles, the check engine light may be reset automatically by the PCM.
To clear the codes, you’ll just need to press the “clear codes” or “erase codes” prompt on the scan tool.
Sometimes, a cracked or loose gas cap can trigger a CEL because the EVAP system will detect a large leak. Some platforms will actually have a fuel cap loose light for this code that will also light up.
Turning off the engine and starting it again can sometimes remove the CEL. Depending on the issue, it might take several restarts before the CEL turns off. However, if your vehicle has a problem, then there’s a good chance the CEL will persist. Again, if the problem was intermittent and doesn’t return within a couple of days, typically the light will reset itself.
As mentioned earlier, sometimes, a CEL can turn off on its own after driving normally. This might be a sign that your vehicle has a minor and intermittent issue.
Yes, you can. However, ignoring the CEL has its associated risks. If you ignore the light or think you know why it is illuminated and keep driving, other issues will pile up behind the first one and you may have a lot more that needs fixing when you finally get other symptoms.
Sometimes, the light can blink. If the light is illuminated red or if it’s blinking, then you have a severe issue that needs to be immediately addressed. Ignoring these signs can permanently damage your engine because it might have low oil levels or misfires.
Ignoring the light and putting it off can result in more engine or transmission-related issues, which will be more costly and time-consuming for you in the future. An illuminated CEL is also considered an obvious sign that your vehicle has an issue. Hence, your vehicle won’t pass an insurance inspection or emissions testing.
Remember that resetting the engine light removes the warning, but that doesn’t mean the issue is resolved. If you don’t have plans to resolve the issue, then you should reset the CEL at your own risk.
If you’ve successfully repaired the problem causing the CEL, then the light should turn off automatically after some time. The light should turn off after 10 to 20 cycles, where one cycle is the process of turning the vehicle on, letting it run for some time, and turning it off again. On some vehicles, the CEL can turn off after driving 50 or 100 miles.
If a CEL illuminates because of an unsealed gas cap, screwing the cap properly will turn off the CEL. However, the vehicle might take up to three or more cycles before the light is turned off.
The engine light is meant to tell you to have your vehicle checked. Sometimes, this warning can go away if the problem isn’t significant. If you want to remove the warning for your peace of mind, the best option is to reset the light by resolving the issues that are causing it.
Once you’ve found the right scan tool for your car, the next thing to do is to order from a trusted source. CarParts.com has high-quality auto parts and tools at varying price points to ensure you have a scan tool that fits your budget.
Simply download our app, and complete your purchase in just a few taps–it’s that easy. Use our vehicle selector to start browsing our selection of auto parts, accessories, and tools.
Adjust the search filters to shop according to your preferred brand, price range, quantity, etc. Rest assured that you’re getting the best deals online with our price match guarantee.
Place your order today, and we’ll deliver it to your doorstep in as fast as two business days.
Check out our catalog and shop now!
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.