Why is my check engine light on but everything is fine?

These problems can range from faults within the electrical system, the engine, fluid levels or to problems within the car's emissions system. The problem can even be as simple as forgetting to tighten your gas cap – in fact, this is the most common reason why check engine lights appear in the first place.
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Why is my engine light on but nothing seems wrong?

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.
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Why is my check engine light on but my car runs fine?

Check Engine Light False Alarms

Sometimes you'll notice a check engine light even though the car runs fine. There are a couple of reasons why this may be. If there is a problem with the car, it's probably the O2 sensor. This is an extremely common problem with modern cars and a relatively easy one to fix.
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Can your check engine light come on for no reason?

The check engine light can come on for many reasons. For example, something as simple as a loose gas cap can trigger the warning. And major problems, such as failed internal engine components, can turn on the light, as well.
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What is the most common cause of check engine light?

The top 25 repairs account for 62% of all check engine repairs in the United States. Replacing a faulty oxygen sensor — a sensor used to optimize a vehicle's fuel-to-air mixture to increase gas mileage and reduce emissions — is the most common cause for a check engine light.
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Most Common Reasons Your Check Engine Light Is On



Is a solid check engine light serious?

If the engine light comes on solid, it may still be a reason for concern, however it doesn't immediately need to strike fear in your heart. A solid Check Engine Light can mean something like a loose gas cap, or it can indicate a more in-depth problem like a fuel, timing, or transmission issue.
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Why is my check engine light on but no codes?

While it is a rare occasion, there are reasons that the Check Engine Light is on, but no codes are showing. If you can't pull any codes, it's most likely due to having the wrong scanner or one that is incompatible with your vehicle.
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Is it safe to drive with check engine light on?

The rule of thumb is that if the check engine light is flashing, you can't keep driving the car. It's an emergency. Often it indicates an engine misfire. If you keep driving, you will likely cause irreversible damage, mostly to the (expensive) catalytic converter.
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How far do you have to drive to reset the check engine light?

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.
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Can an oil change cause the check engine light to come on?

Oil changes are essential maintenance for your car but it won't do anything that could trigger your check engine light to come on.
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Why did my engine light come on while driving?

Oxygen Sensor

A faulty oxygen sensor will return a check engine warning every time. In fact, it's one of the most common reasons why a check engine light comes on while you're driving your automobile.
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Can a gas cap cause the engine light to come on?

Fuel System Issues

Faulty gas cap - Your vehicle is pretty good at warning you of any potential trouble. Something as simple as forgetting to replace the gas cap could cause your “check engine” light to come on. This is because the gas cap keeps vapors from escaping the fuel tank.
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Can Autozone clear my check engine light?

Let's first start with a little information. Did you know that you can get your check engine light scanned for free? Any of the major parts stores in the country, such as: Napa, Advance Auto, Autozone and O'Reilly's, will scan your vehicle, and tell you the P codes for no charge at all.
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How long can I drive with check engine?

How Many Miles Can You Drive With Check Engine Light On? You should drive your car 30 to 100 miles in order to ensure that the check engine light does not reappear. As the sensors need time to calibrate, the vehicle's “Drive Cycle” can be reset.
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How do you diagnose a car without OBD?

Press the odometer's Trip and Reset buttons while turning the ignition key ON. After turning the key ON, release the odometer Reset and Trip buttons to check if the Diagnostic Trouble Code or DTC appears on the odometer display.
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Will check engine light come back on after reset?

If there's a problem, the light will just come back

When you reset your computer's memory, the warning light will turn off. However, if there's a problem, the light will come back on as soon as the computer runs the test that caused the light in the first place.
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What does a yellow check engine light mean?

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.
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How much does it cost to reset check engine light?

The national average repair cost linked to a car or truck's check engine light now stands at $357, including parts ($216) and labor ($141).
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How long does it take for check engine light to clear after gas cap?

As soon as it's safe, pull over and make sure your gas cap is tight. Once you're back on the road, your check engine light should go off within 10 or 20 miles.
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How do you check for a gas cap leak?

If you experience a strong gasoline smell around the time the check engine light comes on, then that is a sure sign you have a leaking gas cap. If you do not notice a smell, be sure to check for a leaking gas cap anyway. It is always better to be safe than sorry when it comes to your vehicle.
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What are the symptoms of an EVAP leak?

Symptoms of an EVAP Leak
  • Fuel Smell. One of the most obvious signs that you are facing an EVAP leak is the smell of fuel. ...
  • Check Engine Light. One of the first symptoms of an EVAP leak is also the presence of the Check Engine Light. ...
  • Poor Engine Performance. ...
  • Hard Start. ...
  • Failed Emissions Test.
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How often should a gas cap be replaced?

Unless your gas cap goes missing, you don't need to replace it anytime soon. Gas caps are designed to last 50,000 miles or more. So long as you are taking your car in for routine maintenance, you will be immediately notified if there's ever an issue with your gas cap by your trusted Indianapolis auto mechanic.
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How do I know if my car has a gas leak?

Driving with a leaking gas tank is a surefire way to spend more on fuel, but doing so is also dangerous.
...
You Smell Fuel Coming From Your Vehicle
  1. You are driving the car down the road.
  2. You walk up to your parked vehicle.
  3. Your car is idling at a stop.
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