Check Engine Light - Five Common Causes


You're driving along minding your own business when all of the sudden a little yellow light pops up on your dash. It's a funny-looking symbol, and it may or may not have the words 'check engine light' displayed. This little light is easy to ignore if your car seems to be running well, but your car is telling you something's wrong, and you ignore that signal at your peril.

Many shops offer free check engine light diagnostics, where the auto technician plugs a small computer into a slot under your dash and a coded message appears. The auto mechanic deciphers the code and lets you know what's wrong with your vehicle. In many cases the light is just signaling that it's time to check, service or replace a certain component. Listed below are five common causes for the check engine light to come on, according to a study done by CarMD.

Faulty Gas Cap

Check this before anything else. If your gas cap is broken, missing or loose, fuel vapors leaking out, throwing your fuel system out of balance. Leaking fuel vapors can reduce fuel efficiency and increase emissions, so check your gas cap to see if its loose or cracked, and tighten or replace it with a new cap from your local auto parts store for just a few bucks.

Faulty Spark Plugs or Wires

Spark plugs seal the combustion chambers and provide the spark that ignites fuel vapors. Like tires, they wear out and fail over time, causing misfiring that can be felt as little jolts in acceleration. Older spark plugs (pre-1996) typically have a lifespan of 25,000 to 30,000 miles, while newer plugs can last as long as 100,000. Spark plugs are fairly inexpensive, and replacement is straightforward.

Faulty Mass Airflow Sensor

This MAS measures the amount of air coming into the engine, communicating with the vehicle's computer to achieve an ideal air-fuel mixture. The sensor can fail over time, party depending on how often the air filter is replaced. A faulty mass airflow sensor will lead to higher emissions, lower gas mileage and more frequent stalling. Replacement sensors are generally a couple hundred dollars, and hiring a mechanic for a little more is a good idea to prevent installation errors.

Faulty Catalytic Converter

The catalytic converter is designed to reduce harmful emissions by converting carbon monoxide and other hazardous gasses into more harmless emissions. Catalytic converters can fail due to faulty oxygen sensors or misfiring spark plugs, and if notice decreased fuel economy or a reduction in acceleration, the catalytic converter may be the cause. Failure leads to a significant increase in the output of dangerous emissions, and since it's especially important in the State of California to keep emissions down to acceptable levels, you'll save money if you take care of this one right away. The cost of a catalytic converter replacement can be upwards of $2,000, so it's very good idea to see what's wrong as soon as the engine light comes on since you may only need spark plugs or an airflow sensor at that time.

Faulty Oxygen Sensor

Your vehicle's oxygen sensors are located in the exhaust system and are designed to measure the amount of unburned oxygen coming out of the tailpipe. This information allows the computer to adjust the air-fuel ratio to achieve an ideal mix, but over time the sensors become covered in burned oil ash and other pollutants, causing them to fail. As a result, your engine begins to run a too rich or too lean air-fuel mix, causing a reduction in gas mileage and increased emissions. If a faulty oxygen sensor goes too long before replacing, you catalytic converter can sustain damage as a result, leading to a much more costly repair. A check engine light diagnostic performed by a qualified and experienced professional will tell you which sensor needs to be replaced to avoid this, and it's usually a very quick fix. Don't put it off!

If your check engine light has just come on, don't delay. In the Covina area, call Hye-Tech Auto at (626) 332-5452 for a FREE check engine light diagnosis.


Hye Tech Auto Blog

Written & Published By MORBiZ



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Check Engine Light
Five Common Causes