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Check Engine Light Triggers

check engine light triggers

The orange, engine-shaped icon on your car dashboard is programmed to turn on when the vehicle detects something is wrong. First – Do not panic!! The Check Engine Light (CEL) does not mean you will need to save your next two paychecks to pay for an expensive repair. Sometimes there are basic, quick and easy fixes for check engine light triggers.

Check Engine Light Triggers?

Even though there are some simple diagnose and repair solutions to a check engine light, this does not mean you can ignore it. Above all, get it checked out as quickly as possible. Here are common problems that can trigger a check engine light.

Oxygen sensor failure

The oxygen sensor (O2 Sensor) measures the amount of unburnt oxygen in a car’s exhaust system. It sends information to the vehicle’s onboard computer, which uses it to regulate the mixture of air and fuel when entering the cylinders. An engine will keep running even if an O2 sensor needs to be replaced, but it will burn more fuel than usual. In the long run, a bad O2 sensor can damage components like spark plugs and the catalytic converter. It may also cause a car to fail an emissions test.

On average, a quality O2 sensor will set you back about $175, but the cost of labor will vary greatly depending on the vehicle’s make and model. Finally, keep in mind that most late-model cars have more than one O2 sensor.

Loose fuel cap

A loose gas cap is one of the MOST COMMON check engine light triggers. The cap is a vital part of a car’s fuel delivery system. It prevents gasoline fumes from leaving the fuel tank, and it helps keep the whole system under the correct pressure.

If your check engine light turns on immediately after a fill-up, pull over and make sure the cap is not loose — or maybe left on the trunk! Sometimes the cap needs to be replaced. Most auto parts stores carry universal-fit gas caps that cost somewhere in the vicinity of $15.

Catalytic converter failure

The catalytic converter is incorporated into a vehicle’s exhaust system. It turns the carbon monoxide generated during the combustion process into carbon dioxide. It is a simple part, and its failure can be prevented. That is the good news because a new one costs between $200 and $600 depending on the make and model. Every late-model car that runs on gasoline has a catalytic converter.

Regular maintenance (such as oil changes) is key to keeping your car’s converter in working order. If you live in the city and mostly drive short distances, take your car on the highway every now and then to ensure the catalytic converter does not get clogged. And as always, keep your eyes and ears open for unusual sounds or discolored smoke coming from the exhaust.

Spark plug

An ignition coil generates the electricity the spark plugs need to ignite the fuel and air mixture in your car’s cylinders. Classic cars have a single coil, but many modern vehicles use one coil per cylinder. If you have a V8 under the hood, you could have eight separate coils. Whether it is one or 16, a malfunctioning coil will almost certainly trigger the check engine light.
Worn or fouled plugs can cause a variety of issues including an engine misfire and hesitation under acceleration. A worn coil can exhibit the same symptoms and can cause the car to shut off unexpectedly. A quality spark plug costs between $10 and $20, while a coil is generally in the $50 range.

The spark plug wire transfers electricity from the coil to the spark plug. Without it, the fuel and air mixture in the cylinders would not ignite. Most cars use a single wire per cylinder, but there are models —some older Mercedes-Benzes — with two spark plugs per cylinder, and consequently two wires.

Symptoms of bad spark plug wires include a rough idle, a noticeable drop in engine performance, and lower gas mileage. Expect to spend about $50 for a set of plug wires.

Mass airflow sensor failure

The mass airflow (MAF) sensor monitors how much air enters the engine. It is a part of the engine management system, your car would not be able to adjust to changes in altitude without it. Symptoms include a rough idle, trouble starting, and a sudden change in the position of the throttle pedal. A MAF for a late-model car typically costs between $120 and $150.

Issues with an aftermarket alarm

An aftermarket alarm can wreak havoc on your car if it is not installed properly. It can drain the battery, trigger the check engine light, or even prevent the vehicle from starting. Then it will go off in the middle of the night because a leaf from a tree fell on the hood!! If you think a faulty alarm install is causing you problems, you will need to have the alarm fixed, reinstalled, or replaced entirely by a knowledgeable mechanic.

Car vacuum hoses

Every car has a vacuum system to perform a wide variety of functions. The vacuum system also helps lower harmful emissions by routing the fumes as gasoline evaporates through the engine. If your car’s idle begins to surge or settles at an unusually high rpm, a vacuum leak could be the reason.

Vacuum hoses can dry out and crack as they age, especially if they are exposed to intense heat or extreme cold. (Hello Midwest!) This is the most common cause of vacuum leaks. Other common issues include cracked fittings and loose connections. Vacuum lines cost just a few bucks each but tracing the source of the leak can be time-consuming — and expensive.

Exhaust gas recirculation valve failure

The exhaust gas recirculation (EGR) system lowers the amount of nitrogen oxide coming out of the car’s engine and helps it run more effectively. It directs the hot exhaust gases back into the combustion chambers, which warms up the fuel and makes it easier to burn. It also reduces emissions. If the valve needs to be replaced, expect to pay at least $125 for a brand-new, OEM-quality unit.

Dead battery

Yes, the battery is important. Without it, your car will not start, light up the road ahead, or (ghast!) charge your phone. Today’s batteries last much longer than before. The price of a new one depends on o the type of car you drive, but plan on spending at least $100 for a quality battery.

Let’s Recap: Check Engine Light Triggers

The check engine light provides an idea — sometimes precise, sometimes vague — of what is wrong with a car. However, it does not replace a skilled mechanic or routine maintenance.

Do not wait until the check engine light comes on to get your car maintenance done. People think the check engine light serves the same purpose as a check-up reminder when it really alerts you, you’re probably due for a pricey engine repair. By that point, the damage has already happened.

Car maintenance is a two-step process. The first and most critical is routine, preventative maintenance. The second is timely diagnostic maintenance which is responsive to changes like new sounds, smells, or feels as you drive.

You also want to be familiar with your car’s basic needs, like how often to change the oil and coolant or replace brake pads. A little research into your vehicle and basic mechanics can save you time and money in the long run. If you are consistent with a regular maintenance routine, you may never see that little orange engine warning light pop on at all.

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