Five Reasons Why Your Vehicle’s Check Engine Light Is On (2023)

FAQs

What is the most common reason for check engine light? ›

The emissions/exhaust system is the most likely culprit for many check engine lights being illuminated. There could be an exhaust leak or a problem with the catalytic converter. The mass airflow sensor (MAF) is another sensor that is easily tripped or can fail.

Sometimes, the check engine light comes on to let you know that there's a problem with the car's internal diagnostic mechanism. That means the system could be “finding” a problem that doesn't exist, or it could be that loose wire systems are creating a false positive in the system.

If nothing seems to be acting strange, then it is probably safe to drive it until you can get it into a mechanic. Sometimes the light may come on after fueling if the gas cap is a little loose. Or it could mean your catalytic converter needs to be inspected.

1) Check your gauges – Look for an indication of low oil pressure or that your vehicle is overheating. If either of these issues are present, turn your vehicle off to prevent any further damage. 2) Inspect the condition of the battery and charging system – If you lose power from the battery, your vehicle will die.

The check engine light, or malfunction indicator light, usually means that your car is experiencing an engine problem. But it can come on for many other reasons, ranging from a simple loose gas cap to a more serious bad catalytic converter. Furthermore, what triggers the light varies by year, make, and car model.

Regardless, diagnosing the problem is key. One thing that won't trigger a check engine light: a recent oil change that was done correctly. Oil changes are essential maintenance for your car but it won't do anything that could trigger your check engine light to come on.

The Gas Cap Trick

Simply remove your gas cap and put it back in place. Turn your car on, and the engine light may already be reset. If not, it might take a few cycles of turning your car off and on to make it reset. In some cases, it helps to drive around for a few miles, too.

Grab your gas cap and twist it. If it is loose, the fumes released will trigger your check engine light to pop on. Inspect your gas cap for wear and tear. A cracked or damaged gas cap will also turn on the engine light.

The on-off method is the equivalent fix for a vehicle's check engine light. It forces the computer to refresh its saved state through a reboot. Simply place your key into the ignition and turn it on for 1-2 seconds, then turn it off for 1-2 seconds. Repeat this step three or four times.

A steady check engine light indicates a non-emergency issue, such as a loose gas cap. Flashing check engine lights warn of severe situations requiring immediate attention. Standardized diagnostic codes help identify the trouble.

Can I reset check engine light myself? ›

To reset a check engine light without a scanner, disconnect the negative battery cable and wait a few moments. This will reset the diagnostic system in your vehicle, and if the underlying issue has indeed been resolved, the light should go off immediately.

Another common cause for a check engine light to come on is low tire pressure. Not all vehicle's are designed with a malfunctioning indicator lamp that will detect this issue, but most newer models do.

In some instances, vehicles check engine lights will turn on after water is detected in the fuel system. This happens after a sensor relays a message to the onboard computer. But to find out exactly what's happening, you'll likely have to take your car to a mechanic.

If it does not click in place or is loose after clicking into place the cap needs to be replaced. The check engine light should go off after you drive for several minutes if the light was caused by a loose gas cap. Pay attention to the dashboard after the check engine light experience.

A dirty air filter can cause your vehicle to throw a Check Engine code. During this instance, the Check Engine Light of your vehicle will turn on. The light turns on because your vehicle is sensing that its engine isn't receiving enough air.

How long can you drive with the check engine light on? Once you see the check engine light, it is safe to drive with the light on for 50 to 100 miles. This is because if the issue is with the sensors, then this will buy some time for it to reset, turning the check engine light off.

On some cars, a yellow check engine light means investigate the problem and a red one means stop right now. Try tightening your gas cap. This can often solve the problem. Keep in mind that it may take several trips before the light resets. Some vehicles have a separate indicator that warns of a loose gas cap.

From check engine lights and spark plugs to serpentine belts and radiator hoses, Jiffy Lube^® can help maintain your engine's optimal performance, reliability and longevity.

The most common symptom of bad gas caps is going to be a gas cap that will not tighten completely or a gas cap that is loose. This might not seem significant at first, but without an air-tight seal, the entire fuel system can be exposed to grime and dirt.

Many manufacturers recommend tightening the fuel cap until it clicks three times, which is just a random number to make sure the cap is tight. At this point — even though the engine will run fine — it would be best to bring the car into have it looked at.

What happens when gas cap is left off? ›

A loose gas cap will not only let in grime and dirt, but it can allow fuel vapors to escape the fuel tank. These vapors can produce an error in the emissions system, which could cause the check engine light to illuminate. Dirt and Grime that gets into the fuel tank can also contaminate the injectors.

Do not overtighten your gas cap. Listen for one click and stop, otherwise you can damage the seal and your check engine light may come on. Never buy aftermarket or locking gas caps. They do not seal properly most of the time and may cause your check engine light to come on.

An ill-fitting gas cap will not only let in grime and dirt, but it can also allow fuel vapors to escape the gas tank. These vapors may cause an error in the emissions system, which would light up the check engine light. Dirt that seeps into the gas tank may also damage fuel injectors over time.

There are some who believe that lidlessness is no big deal. But those some are wrong. A broken or missing gas cap can reduce your fuel efficiency by 1% to 2%. You see, the gas cap keeps evaporates and --believe it or not--gas in its proper place.

In most cases, a check engine light will shine steadily, a serious reminder that something is amiss in your vehicle. If the light is blinking, however, your minor annoyance and concern just got elevated. If the check engine light is blinking, get to the nearest trustworthy mechanic you know.

A flashing orange light means that there is a problem that could affect how the car drives or handles, such as an engine misfire. You might be able to feel your car shake, or the engine could suddenly sound different. If this light comes on, you should take your car to be inspected immediately.

If the tire pressure warning light on your dashboard remains on after a long while, it's an indication that one or more of the tires is leaking air. If the TPMS warning light flashes on for 1 second, then off for 3 seconds repeatedly, this is an indication that the vehicle has issues with one or more of the sensors.

If you've been driving and slowly begin to notice that driving the vehicle seems softer, almost sponge-like, this is a sign of low tire pressure. As the tire pressure decreases, the tire begins to flatten out. This more of tire's service area is making contact with the road, creating the spongy feel.

Inflate your vehicle's tires to three PSI above the recommended level, then completely deflate them. Ensure you do this for your spare tire also, as it may hold a sensor. Once every tire is deflated, inflate them to the recommended tire pressure to reset the tire light.

If you have a tank of bad gas in the car, your check engine light may come on. For example, if your vehicle is designed to run on premium gas (octane grade 91 to 94), the engine may struggle to run on regular gas (octane level 87). You can safely solve this problem by having a professional drain your gas tank.

What additive removes water from gas tank? ›

Iso-HEET®Opens a new window is a fuel additive specifically made to remove water from the gas tank. However, if there is more water in the tank than gas, there's no fuel additive on the market capable of getting the job done because the ratio is off.

For a typical 40-gallon fuel tank, one half to one pint of isopropanol will disperse the water and get your engine running satisfactorily.

To make sure the check engine light does not reappear, it's recommended that you drive your car 30 to 100 miles. This enables the vehicle's “Drive Cycle” to reset, as the various sensors need time to recalibrate.

Yes they can make the light go out temporarily.

They do it by using a scanner to erase the readiness monitors. Then until the readiness monitors reset (might be days, weeks or months) the light will stay off. That is, unless there is a hard failure then the light will come back when the car is restarted.

Can you drive a car with the engine light on? It's okay to drive for a few miles, but be sure to schedule an inspection of the engine as soon as possible. If the check engine light comes on while you're driving, don't panic! Pay attention and see if the car is driving any differently than normal.

A steady check engine light indicates a non-emergency issue, such as a loose gas cap. Flashing check engine lights warn of severe situations requiring immediate attention. Standardized diagnostic codes help identify the trouble.

So why is the light still on? Here's something you probably don't know: after clearing the car's computer you will need to drive for about 50 to 100 miles.

In most cases, a check engine light will shine steadily, a serious reminder that something is amiss in your vehicle. If the light is blinking, however, your minor annoyance and concern just got elevated. If the check engine light is blinking, get to the nearest trustworthy mechanic you know.

Permanent Diagnostic Trouble Codes (PDTCs) are very similar to regular Diagnostic Trouble Codes (DTCs). However, unlike regular DTCs, they cannot be reset by disconnecting the vehicle's battery or cleared using an On-Board Diagnostic (OBD) scan tool.

The check engine light should go off after you drive for several minutes if the light was caused by a loose gas cap. Pay attention to the dashboard after the check engine light experience.