Service Engine Light

What Caused My Service Engine Light To Turn On?

Research shows that nearly 30 percent of drivers in Asheville tend to ignore their service engine lights. Unfortunately, this makes them far more likely to experience an unexpected breakdown. With the use of advanced diagnostic equipment, a professional mechanic can quickly track down the source of the trouble code. Here are some common problems that will trigger a service engine light.

Loose Gas Cap

Service Engine LightYour vehicle’s onboard computer can almost instantaneously detect a loss of pressure inside the fuel tank. If your service engine light suddenly turns on after refueling, there’s a good chance you simply forgot to tighten the gas cap. Although a loose or missing gas cap may not seem serious, this issue can cause trouble in the long run.

For starters, a loose gas cap allows fumes to escape. This problem contributes to environmental pollution. Over time, you may also notice that your vehicle’s fuel economy has taken a hit. While it’s okay to drive without a gas cap for a few days, don’t make it habit.

Bad Oxygen Sensor Triggers Service Engine Light

After your vehicle surpasses the 60,000-mile mark, it’s far more likely to encounter a bad oxygen sensor. This sensor’s job is to monitor unburned oxygen coming out of your exhaust, which allows the onboard computer to properly adjusts the engine’s air-fuel ratio. When it fails, expect to see a glowing service engine light.

Most modern vehicles feature at least two oxygen sensors. The pre-cat oxygen sensor is the one that usually causes performance issues. A rough-running engine is especially common. Bad gas mileage is another problem that stems from a bad pre-cat oxygen sensor.

Bad Spark Plugs

When your vehicle is in dire need of a tune-up, its service engine light is usually activated. A mechanic must replace the spark plugs and ignition wires. This is a critical aspect of any vehicle’s factory recommended maintenance.

Bad sparks usually cause rough idling, hesitation, and hard starting. If you continue to drive your vehicle with worn-out spark plugs, things will only get worse. In some instances, your vehicle may even to even crank. The good news is that modern spark plugs have a long lifespan. Some are rated to last for more than 100,000 miles.


Engine overheating is among the most serious car problems of all. Aside from a service engine light, you’ll also likely notice stem escaping from underneath the hood. At this point, be sure to pull over as soon as possible. When an engine has started to overheat, it can self-destruct in less than a minute. From a blown head gasket to warped cylinders, several major problems may occur.

The root of the problem could be a low level of coolant, which often stems from a leaky hose or busted radiator. While adding more coolant may temporarily solve the problem, you’ll ultimately need to have the leaked professionally repaired.

Bad Catalytic Converter

Designed to help limit harmful exhaust emissions, the catalytic converter is one of the most important parts on your vehicle. When this part fails, your vehicle’s service engine light will turn on.

Oftentimes, catalytic converters fail as a result of poor maintenance. For instance, misfiring spark plugs can allow raw fuel to get into the catalytic converter. This could cause the ceramic material inside the catalytic converter to melt. Motor oil leaks can be just as damaging.

Engine Overload – Service Engine Light

Vehicles that are used for towing are more prone to experiencing engine overload. This is why it’s important to adhere to the manufacturer’s maximum tow rating. Too heavy of a load puts unnecessary stress on the engine, which could lead to big trouble. If your service engine starts to flash repeatedly, pull over and shut off the vehicle. To be on the safe side, the best approach is to call for a tow.

Cox Auto Service