The check engine light always seems to flash at the worst possible time. Either you just got your car out of the shop, are about to head out on a big road trip or you were just telling a friend how reliable your car is.
Regardless, the check engine light is not something you should ignore. Sometimes, you get lucky and it’s an easy fix. Other times, it signals that a serious repair is needed. Either way, the sooner you can diagnose the issue, the faster you can get your car fixed.
These are some of the most common reasons for check engine lights, according to the CarMD Vehicle Health Index.
Average repair cost: $1,356
Of the top 10 reasons for check engine lights, replacing the catalytic converter comes in at number one. The catalytic converter turns carbon monoxide found in exhaust gases into less harmful emissions. Without it, your car won’t go, and if it does, it will get horrible gas mileage.
The good news is this part should not fail if you are keeping up with your car maintenance. The main reasons for it failing are faulty oxygen sensors and bad spark plugs, which your mechanic should be checking when your car goes into the shop.
A failing catalytic converter would be noticeable as it may cause reduced acceleration, sluggish engine performance, dark exhaust smoke and heat under the engine.
Average repair cost: $243
Oxygen sensors can fail due to lack of maintenance like neglecting oil changes.
Most cars have two to four oxygen sensors. They measure the amount of unburned oxygen in the vehicle’s exhaust system. If one fails, the vehicle could burn more fuel than is needed.
Many drivers ignore the O2 senor because it doesn’t typically affect how the car performs, but if you don’t address the issue, it will reduce your fuel economy and slowly damage you car. It could eventually bust your catalytic converter, a much more expensive repair.
Ignition Coils and Spark Plugs
Average repair cost: $387
These parts help start a car. The spark plugs ignite the mixture of air and gas found in the combustion chamber and spark plug wires deliver the spark needed to do this from the ignition coil to the spark plugs. All very cool stuff, and all parts that degrade and could fail over time.
Spark plugs can usually last up to 100,000 miles, but they don’t always. A good mechanic will inspect them routinely.
If you ignore spark plugs long enough you could experience reduced engine power and fuel economy or damage the catalytic converter.
Loose or Damaged Gas Cap
Average repair cost: $25
As the price tag indicates, this is an easy and inexpensive fix for your check engine light.
If the gas cap is broken or loose, the vehicle’s fuel system gets thrown out of whack. You probably won’t feel or notice anything different about how the car drives, so it may come as a surprise.
If your check engine light comes on without warning, the first thing you should do is tighten the gas cap and check it for cracks. Rather than bring it to the shop, this is a repair you can do yourself. A new gas cap should cost you less than $15.
Mass Air Flow Sensor
Average repair cost: $319
This sensor works with the vehicle’s computer to get the right mix of air and fuel in the combustion chamber. If it fails, so can your car. Rough idles and stalls are all but assured when this happens.
Like some of the other problems on this list, an unchecked mass air flow sensor will decrease your fuel economy and can damage your spark plugs, catalytic converter and oxygen sensor, resulting in a mega-repair with a big price tag, so don’t hesitate to bring to a trusted mechanic.
Lesson learned? Avoid the dreaded check engine light by staying up on your car maintenance.
If you need a mechanic, search our list of reputable AAA Approved Auto Repair facilities in your area.
And if your check engine light turning on is the latest in a series of ongoing car problems, it may be time to invest in a new set of wheels. Learn about the benefits of the AAA Auto Buying program.