5 Common Car Problems and What They Cost to Fix

By Dee-Ann Durbin, AP Auto Writer

DETROIT (AP) — Drivers get nervous whenever the "check engine" light illuminates on their dashboard. It can signal anything from a missing $3 gas cap to repairs costing thousands of dollars.

But think of the light as a way to stay on top of problems and extend the life of a car. Often, it's warning about problems that can be avoided by keeping up with regular maintenance, says CarMD, a maker of vehicle diagnostic equipment.

While maintenance is expensive, it's crucial as people hang on to their cars longer. According to R.L. Polk, an automotive data firm, the average vehicle on the road is now 10.6 years old, up from 8.8 years a decade ago.

Here are the five most common reasons your "check engine" light might come on, and what you can expect to pay for the repair, including labor, according to CarMD:

1. Faulty oxygen sensor:

The sensor measures the amount of unburned oxygen in the exhaust and tells the car's computer how much fuel is in the tank. If a faulty one is not repaired, the car's gas mileage could drop, since the sensor is sending incorrect information to the car. It costs less than $200 to repair.

2. Loose or missing gas cap:

Technicians will often tighten the gas cap for free, or replace it for a few dollars. If it's not replaced, gas will evaporate from the car and decrease its gas mileage.

3. Broken catalytic converter:

This one isn't good news, since it can cost up to $2,000 to replace. The catalytic converter uses a catalyst — most often a precious metal such as platinum — to convert harmful gases left over from combustion to less harmful emissions. CarMD says catalytic converters generally won't fail unless a related part, such as a spark plug, malfunctions, so it's wise to keep up with the car's maintenance schedule.