Five Reasons Your Check Engine Light is On | Denver CO

Is your Check Engine Light on and you're wondering what it could mean?

Check out the Top 5 Reasons Your Check Engine Light is On below. If you still have check engine light questions or need check engine light service, call our team at 877-453-2234. Our Aurora service department team will help you with your vehicle repairs and get you back on the road!

1. Replace Oxygen Sensor

An oxygen sensor monitors the un-burned oxygen from the vehicle's exhaust. It detects how much fuel is burned. A faulty oxygen sensor means it's not providing the right data to the computer and causes a decrease in gas mileage. Most cars have between two and four oxygen sensors and the trouble code, from a diagnostic test will tell you which one needs replacing.

What causes it: Over time, the sensor gets covered with soot build up and reduces the sensors ability to change the oxygen and fuel mixture. A faulty oxygen sensor may not only decrease your gas mileage, but it also increases your vehicle's emissions.

What you should do: If is determined that your Oxygen sensor is faulty; not replacing it could lead to a broken catalytic convertor which can cost over $2,000 to replace. a broken sensor should be fixed ASAP.

2. Loose or Defective Gas Cap

When a gas cap is loose or cracked, fuel vapors leak out and can throw the fuel system off balance. This causes reduced gas mileage and increases emissions.

What causes it: If you get a trouble code pointing to the gas cap fuel vapors are leaking out of your cap. This means the cap is either cracked or perhaps not tightened enough.

What you should do: If your car isn't feeling strange, when the check engine light comes on, the first thing you should check is the gas cap. Look at the cap to see if it has any cracks in it, replace and re-tighten the cap. Drive and see if the check engine light turns off. You can replace the gas cap yourself for less than five dollars.

3. Replace Catalytic Convertor

The catalytic convertor works to reduce exhaust fumes. It converts carbon monoxide and other harmful gases into harmless compounds. If your catalytic convertor is failing, you'll notice a decrease in gas mileage or your car won't pick up speed when you push the gas pedal.

What causes it: If you're keeping regular maintenance Catalytic convertors shouldn't fail. The main cause of failure is related to other items mentioned, including a broken oxygen sensor or failing spark plugs. When it fails, it stops converting carbon monoxide into less harmful exhaust emissions.

What you should do: With complete catalytic convertor failure, eventually your vehicle's engine will not stay running. You should try and fix it as soon as you can because your gas mileage will also be poor. Unfortunately, the average replacement cost is around $2,000 and you can't do it yourself unless you're an experienced mechanic.

4. Replace Mass Airflow Sensor

The mass airflow sensor tells your vehicle's computer to add the proper amount of fuel based on the air coming through to the engine. A faulty mass airflow sensor can increase emissions, cause your vehicle to stall, and decrease gas mileage.

What causes it: Most mass airflow sensors fail because of an improperly installed (or never replaced) air filter. You should replace the air filter at least once a year to help prevent the airflow sensor from failing.

What you should do: You can drive for a few weeks with a broken mass airflow sensor, but you will notice a decrease in gas mileage and your vehicle will often stall.

5. Replace Spark Plugs and Wires

The spark plug seals the combustion chamber and provides a gap for a spark to jump across and initiates combustion in your engine. When the plugs are failing, the spark plugs misfire. when this happens you will feel a shake in your vehicle's acceleration.

What causes it: Most spark plugs in vehicles from before 1996 should be replaced every 25,000-30,000 miles. Newer ones can last up to 100,000 miles. Still expect, that plugs will naturally fail over time.

What you should do: Get them replaced right away. It's an inexpensive fix and your vehicle will run better. Since this is part of your vehicle's regular maintenance, the spark plugs are usually  accessible from the hood of the car.

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