Don’t Ignore the Check Engine Light! These Are the 5 Most Common Reasons It Lights Up

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That little engine symbol lights up on your dash. Your heart sinks and all you can wonder is how much this round of car repairs is going to cost you. There are many reasons why that light comes on, and with the purchase of an OBD-II reader (or borrowing one from your local shop) you can easily plug it into your car (usually under the dash) and get a code which will tell you your fate. If you don’t happen to have an OBD-II reader in your garage and are sitting around sweating bullets about what may await you under the hood, we’ve assembled the Top 5 Reasons for a Check Engine Light so you won’t have to panic… yet.

5 Catalytic Converter

If your check engine light is telling you there is an issue with the catalytic converter, now its time to cry. Why? Because a catalytic converter is going tocost you in the thousands to fix and the catalytic converter is a legal obligation to have on your car. You also can’t fix the thing yourself, so you’re going tohave to be taking your car into the shop and forking over your hard earned cash. But don’t worry — you should never have to replace the catalytic converter in the first place. However, if you’ve let your car seep into a muddling mechanical mess, it may be next on your list of repairs.

4 Spark Plugs

When your spark plug wires get old, or your current spark plugs are going bad, your car may throw a code and give you the check engine light. You can prevent this problem by knowing what kind of spark plugs you haveinstalled, knowing how many miles they are good for, and checking to see if the plug wires are looking loose or ratty. If you know how to replace plugs and wires (actually very easy on most cars, just learn the basic, yet vital details on how to do it first) this is an easy and fairly cheap fix. Buy good spark plugs that will last around 100,000k miles and good wires. Your local auto parts shop can help you find the best parts and a car repair manual for your year/make/model of vehicle will show you how to do it.


An MAF is a Mass Air Flow Sensor which helps monitor fuel control based on the air flowing through the system. If an MAF goes out, you can expect to get lower MPGs and maybe even a stalling engine from time to time. You shouldn’t have much problem with the MAF if you have installed new air filters on occasion and have had them installed properly (never trust the minimum wage grease monkey). A MAF can cost around $300 to fix (domestic vehicles), but you can do it yourself if need be.

2 Oxygen Sensor

The O2 sensor helps monitor fuel consumption. Don’t sweat though, the O2 sensor going out isn’t the biggest deal in the world, but if you don’t fix it you won’t be able to pass smog/emissions (if your state has those laws) and iteventually may cause problems down the line with the catalytic converter. Also, with aO2 Sensor down, you probably aren’t getting the proper fuel consumption out of your vehicle either. You can most likely go to a shop and have it fixed for under $200 (for a domestic vehicle), but if you’re a little fix-it savvy, the O2 sensor is typically an easy do-it yourself project… though you may have to crawl pretty far under your car to get at the sensor.

1 Loose Gas Cap

If this is the reason your check engine light is on, be thankful. It’s the cheapest of repairs. Sometimes it’s just simply a matter of tightening the cap or jiggling it, other times it may be broken and need to be (cheaply) replaced. You can buy a new cap at your local auto part shop or find one online. This issue will mostly just decrease MPGs, and not by much. It’s so easy and cheap, its better just to get it fixed.

Next time that little engine light flashes up on your dash, don’t panic, and remain calm. Most the time it’s an easy, quick fix you can do yourself or something that won’t break your bank account. A general rule to remember with cars is to always use the best parts, goto a mechanic you trust (or do it yourself) and always keep things well maintained or you’ll end up having more expensive fixes on your plate down the line.

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