what could be causing a decrease in my gas mileage?

Have you suddenly found yourself making more frequent trips to the gas station than you used to? If your driving habits, typical miles traveled, and driving conditions haven’t changed, this could be a sign that something in your vehicle needs attention. With the holiday season on the way and the price of gas expected to stay relatively high through the end of the year, there’s no better time to take care of any needed repairs or maintenance.

Here are some of the most common issues that could be causing your gas mileage to decrease:

Dirty or Damaged Fuel Injectors

Clogged or damaged fuel injectors are one of the most common reasons drivers see a drop in fuel economy. The fuel injectors are small nozzles that spray fuel into each of the engine’s cylinders. For the engine to run at its most efficient, the spray pattern needs to be extremely precise—otherwise, the engine might not have the right air-to-fuel ratio it needs for proper combustion. You may need to have your fuel injectors cleaned or replaced.

Clogged Fuel Filter

Fuel filters keep contaminants in the fuel from reaching your engine, where they can cause damage to the moving parts. If the filter is clogged, it can reduce the fuel pressure, which can lead to misfires, rough idling, difficult starts, and stalling.

Dirty Oxygen Sensor

All newer vehicles use oxygen sensors to determine how lean or rich the exhaust gases are; this information is sent to your car’s computer, where it makes adjustments to how much fuel is entering the engine. If the O2 sensor is dirty or wearing down and working slowly, it can cause your engine to burn too much fuel. In some cases, it could lower your fuel economy by as much as 40%. Faulty O2 sensors are also a common reason for the check engine light to come on, but fortunately, they’re relatively inexpensive to replace.

Dirty Engine Air Filter

To power your vehicle, your engine needs a constant supply of clean air. If the filter is clogged, your engine is essentially struggling to breathe. You may notice poor performance as your engine tries to compensate for a lack of airflow. Although it can vary based on your vehicle, most engine air filters should be replaced around every 15,000 to 30,000 miles.

Worn Piston Rings

The piston rings are located in the engine’s cylinders, where they create a seal against the cylinder walls. When they become worn, the engine loses combustion pressure, and fuel economy goes down. The best way to prevent worn piston rings (and improve fuel efficiency) is to keep up with regular oil changes.

Faulty Ignition Parts

The ignition system is made up of several parts that are responsible for the combustion process in the engine. If any of them are malfunctioning or broken, the air-fuel mixture will be off and you may experience misfires, rough idling, a decrease in engine power—and lower fuel economy. Most ignition system problems tend to be caused by worn spark plugs, faulty ignition coil or faulty spark plug wires.

Incorrect (or Old) Oil

Using the right type of motor oil is essential for keeping your engine properly lubricated and reducing wear and tear. Likewise, the oil needs to be changed regularly, as dirty oil loses a lot of its lubricating and protective properties. If you wait too long to change the oil, it can become sludgy, causing everything from lower performance and gas mileage to potential engine damage.

Dirty Mass Airflow Sensor

The mass airflow sensor is responsible for measuring the amount of air the engine receives. Just like the O2 sensor, it sends this information to your car’s computer so it can calculate the correct air-to-fuel ratio and make adjustments. If the airflow sensor is dirty, the computer will have trouble calculating the right amount of air to fuel. This can affect gas mileage and lead to stalling. Following a recommendation to clean the intake components is always a good choice.

Poor Alignment

Wheel alignment ensures that all four of your wheels are making proper contact with the road and at the right angle. Misaligned wheels create extra resistance on the road, which in turn lowers your gas mileage and makes the engine work harder than it should. They also affect handling—and safety, not to mention tire wear.

Underinflated Tires

Like wheel alignments, underinflated tires increase the rolling resistance and friction as you drive. This is because when your tires are underinflated, they have more surface area to make contact with the road. Running even five PSI below the recommended pressure can create enough drag to lower your gas mileage. Driving with underinflated tires also puts you at a higher risk of tread separation, blowouts, and accidents.

Sticky Brakes

Brake components that are stuck or sticking (like calipers or brake pads) aren’t only a safety issue—they can also create resistance while your vehicle is moving forward. Brake drag resistance causes your engine to constantly struggle to move your vehicle, which can lead to a drastic drop in fuel efficiency.

Improve Your Gas Mileage at Express Auto/RV Care Center

As you can see, there are many factors that can impact your gas mileage; the good news is, you can prevent many of them simply by keeping up with your vehicle’s scheduled maintenance. Whether you’ve noticed your gas mileage has taken a dive or it’s simply been a while since your car was last inspected, you can rely on Express Auto/RV Care Center to help you maximize your vehicle’s road life and potential—and your savings at the gas pump!