An October 2011 article at MainStreet.com lists common types of car repairs. Writer Jeanine Skowronski notes that, unless you’re a professional technician, tackling certain automotive problems yourself may not be the best approach, and could end up costing you more money.

Here are five common car repairs and the problems that can result if they’re ignored or not handled by a skilled automotive technician.

1) Replacing Spark Plugs
Spark plugs are a small part that can cause big trouble. According to CarMD’s Art Jacobsen, faulty spark plugs can reduce your gas mileage or melt your car’s significantly more expensive catalytic converter, so having them replaced by a certified mechanic is worth the expense.

2) Replacing Mass Air Flow Sensor
The mass air flow sensor measures the amount of air supplied to the engine and determines how much fuel should be delivered to it. The need to repair it typically results from not replacing air filters on time. The small cost of a new filter now and then is replaced by the roughly $400 price tag of the new sensor. And you’ll still have to buy a new air filter anyway.

3) Removing an Aftermarket Alarm
Jacobsen says that this is a repair you may bring on yourself if you attempt to install an after-market car alarm, car stereo, DVD players, or other devices on your own. He explains that “when owners add things to their vehicles, they tap into circuits for convenience, but that takes power away from something else” and can potentially lead other systems to fail.

4) Replacing Catalytic Converter
According to Jacobsen, the costliest repair on the list shouldn’t have made the list to begin with. That’s because catalytic converters typically fail only when a smaller, related part – such as a spark plug or fuel injector – is ignored for too long. “It’s a case where not taking care of something small leads to a big repair with a hefty price tag,” he says.  

5) Loose Fuel Caps
A leading reason the pesky “check engine” light turns on, loose or missing gas caps cost very little to fix but can cause car owners tons of money if left unattended, since the problem can result in a 0.5% decrease in gas mileage. CarMD estimates that lost, damaged or missing gas caps cause 147 million gallons of gas to evaporate every year.