A "check engine" or "service engine soon" light can mean many various things, from a misfiring engine to a loose gas cap. Below are the five most common reasons a check engine light will be displayed:
1. Replace the Oxygen Sensor
An oxygen sensor monitors the unburned oxygen from the exhaust. The oxygen sensor monitors combusted fuel. A faulty sensor means it is not providing the right data to your car's computer and causes a decrease in gas mileage.
What causes a faulty sensor?
The sensor gets covered in oil ash over time and reduces the sensors ability to alter the oxygen and fuel mixture. A faulty sensor not only reduces gas mileage, but it also increases emissions.
What you should do
Not replacing a broken oxygen sensor can eventually lead to a broken catalytic converter.
2. Loose or Faulty Gas Cap
A cracked or loose gas cap will cause the fuel vapors leak out, and can throw the entire fuel system off. A loose gas cap causes a reduction in gas mileage and increases emissions. If you get an error designating the gas cap, it indicates fuel vapors are leaking out of your cap. This means the cap is either cracked or not tightened well enough.
What you should do:
If your car isn't riding differently when the check engine light comes on, it is wise to check the gas cap. Re-tighten it, and take a peek at the gas cap to see if there are any cracks. Continue driving, watching if the check engine light turns off. While not car-threatening, it is good to take care of this right away to improve gas mileage.
3. Replace Catalytic Converter
The catalytic converter operates to reduce exhaust gases. It converts carbon monoxide and toxic materials into harmless compounds. If your catalytic converter is failing, you will notice a decrease in gas mileage or your car may not accelerate when prompted.
Catalytic converters should not fail if regular maintenance is upheld. The primary cause of failure is related to other items on this list, including a broken oxygen sensor or deteriorated spark plugs. When it fails, it stops converting carbon monoxide into less harmful emissions.
If your catalytic converter fails, you eventually won’t be able to keep the car running. Your gas mileage will suffer, so it is a priority to have it fixed as soon as you can.
4. Replace Mass Airflow Sensor
The mass airflow sensor tells the car’s computer to add the proper amount of fuel based on the air coming through to the engine. A faulty one can increase emissions, cause the vehicle to stall, and decrease gas mileage.
Most mass airflow sensors fail because of a poorly fitted air filter. Replacing the air filter once a year helps to prevent the airflow sensor from failing.
You can drive for a few weeks or months with a broken mass airflow sensor. At first, you will notice a decrease in gas mileage, but over time your car may start stalling frequently.
5. Replace the Spark Plugs and Wires
Combustion chambers are sealed by spark plugs. They also provide a gap for a spark to jump across to initiate combustion in your engine. Failing plugs mean a spark plug misfire. You will feel a little jolt in your car’s acceleration when this happens.
Most spark plugs in cars from before 1996 need replacing every 25,000-30,000 miles. Spark plugs in cars after 1996 can last up to 100,000 miles. Regardless of how long they last, plugs fail over time.
If you presume your spark plugs are failing, get them replaced right away. Your car will run better for it.
There are many different possibilities for a check engine light to be on; the above five were the most common. There are also different ways your check engine light can present itself. Below are four different scenarios.
1. Your Check Engine Light is flickering or blinking.
If your Check Engine Light comes on in the city but goes off on the highway, then the fault is occurring through city driving conditions. Note if the vehicle runs or drives any differently when the Check Engine Light illuminates. If vehicle performance does change, drive the car as little as possible and bring it to be checked by us at DJ Foreign Auto as soon as you can. No change in vehicle performance means you can drive home, but have us inspect it as soon as feasible. You run a risk of a vehicle that won't start in this condition.
2. The Check Engine Light comes on and stays on.
A Check Engine Light that remains on while driving with no noticeable driving or performance problems means there is a possible permanent fault in the emission control system. You should get the vehicle serviced by us at DJ Foreign Auto as soon as possible. The vehicle will operate, but you run a risk of it dying or not starting.
3. The Check Engine Light illuminates, stays on, with performance problems.
A vital component of your emission control and engine management system has a severe problem. It usually involves an element or system needed for the vehicle to run. Drive the vehicle as little as you can In most cases; it is not safe to drive the vehicle—it could stop or stall at any time. We recommend you pull over safely and have the vehicle towed to us at DJ Foreign Auto for a thorough inspection and repair.
4. The Check Engine Light light blinks in a regular pattern while driving.
Don't confuse this steady pulsing of the Check Engine Light (one+ flashes per second) with a flicker. The Check Engine Light may stay on, or it may flash when the vehicle accelerates. When it does so, it usually means there is a malfunction of the emission control system that is prompting the engine to misfire. Every misfire leads the catalytic converter to be damaged each time the Check Engine Light flashes. The catalytic converter is heating to the point that it will glow red or ignite a fire underneath the vehicle. Promptly pull over to a safe place and have your vehicle towed to us at DJ Foreign Auto for repair. Vehicles can be seriously damaged or destroyed by fire if this condition is ignored for too long.
For all of your BMW, MINI, Mercedes, Jaguar, Land Rover and other European vehicle repair and maintenance needs, call today to get on the schedule: 612-567-5908. DJ Foreign Auto Care is located at: 2626 University Ave NE, Minneapolis, MN 55418.