Five Biggest Reasons Why The “Check Engine” Comes On

Common Check Engine Light Culprits

It's one of the worst feelings to have while driving ; the dreaded “Check Engine” light comes on. For a lot of motorists, they feel the doom and gloom of the situation. “Will the engine die?” “Is there smoke coming from the vents?” “Why is the car sputtering?” We’ve all been there and asked those questions to ourselves. While it may spell doom and gloom, it actually provides an early warning system for your car before it suffers internal damage. At Cary Car Care, our mission is to diagnose the problem with our state-of-the-art equipment that will pinpoint the root cause of the issue. Here are the five biggest reasons why the check engine light comes on.

An O2 Sensor Has Started to Fail

A car’s oxygen sensor monitors the unburned oxygen in the exhaust system. Monitoring the oxygen is a way of managing the fuel mixture. This is to ensure the car doesn't run too rich or too lean. When it begins to fail, it may idle at a higher RPM in addition to running rough. Because the sensor can no longer regulate the fuel mixture, a car’s emissions will go up. While O2 Sensors are robust, they are exposed to the elements, and will deteriorate. Once this happens, the sensor will throw a fault, and thus the Check Engine light comes on.

Spark Plugs Have Burned Out

Spark Plugs are basically the conductor of the engine. They provided the necessary spark that ignites the fuel and air mixture that creates engine power. The gap between the ends of the plug is close enough that the electricity will cross the gap between them, giving the ignition the proper voltage. As the spark plug wears, the gap becomes less and less. This causes the engine to misfire, lose power, create excess wear, and lower gas mileage. Over time, a plug’s wear will cause damage to their adjoining plug wires and ignition coils.

Catalytic Converter Has Failed

To help reduce emissions, Catalytic Converters create an oxidizing reaction to lessen the effect of pollutants on the atmosphere. Over the years, they’ve become more integrated with an engine’s management system. This allows it to work more efficiently and reduce wear. On average, a Catalytic Converter lasts around 10 years, so it won’t be a high priority of repair if you buy the new. That said, several factors can lead to it wearing down. If raw fuel or antifreeze find their way into the exhaust system, it could cause the Catalyst to overheat and melt down. Other problems include faulty oxygen sensors, worn spark plugs, and structural damage.

Vacuum Hoses May Be Leaking

Acting as a release valve, vacuum hoses take pressure buildup from engine components to allow for smooth combustion. Like other parts of the engine, the hoses are susceptible to the elements like heat, dirt, and debris. When a hose breaks, the car may start to misfire and perform sluggishly. In most modern cars, there is a sensor that monitors the hoses’ function. If it detects a drop in pressure from a faulty hose, it will signal a fault code immediately. In most circumstances, the hose is just worn out.

Your Gas Cap Is Loose

As strange as it may sound, a loose gas cap can cause your check engine light to come on. Because the cap has a perfect seal on the fuel tank, any that escapes from the tank can be hazardous. A fuel level sensor monitoring it can detect the escaping vapor and send an alarm to your cars’ brain, thus causing the check engine light to come on.

If you experience any of the issues listed above, please don’t hesitate to call us at 919-380-0040 to schedule an appointment. Our ASE-certified technicians will take great care in diagnosing your vehicle. Our shop is located on 234 E Johnson Street near Kingswood Elementary School in Downtown Cary. We look forward to providing good car care for you!

Written by Cary Car Care