Counties in the Atlanta metropolitan area require most vehicles to pass an annual emissions test, and a bad oxygen sensor can cause your car to fail, so don't put off this important repair.
Most cars have one to four oxygen sensors, which measure the oxygen in your car's exhaust and tell the engine's computer whether there is enough gas in the mix of air and fuel being burned in the engine. If a sensor goes bad and produces incorrect readings, it can decrease your car's gas mileage by as much as 40 percent. Check your owner's manual to learn how many oxygen sensors your car has and how often you should plan to change them.
Finding the problem
When your "check engine" light comes on, take your car to a trusted mechanic or auto parts store. Ask them to diagnose the problem with an engine code reader; most auto parts stores will offer this service for free. If the diagnostic code identifies your problem as a bad oxygen sensor, take your car home and look under the hood. Check for disconnected hoses or wires, which are easy to fix at home and can produce the same code as a bad sensor.
If you find a disconnected hose or wire, fix the connection yourself to save on labor charges. However, if nothing is obviously amiss, you will need to take your car to a mechanic. A mechanic will have more sophisticated diagnostic tools to verify the problem. Expect to pay a small fee for the diagnostic service.
Fixing the problem
Do you know your way around a garage? You may be able to change your own oxygen sensors, but make sure you are confident of your car maintenance skills and have the appropriate tools and equipment. Buy a new oxygen sensor at your local automotive store for about $100 and $250, depending on the make and model of your car.
Before you start, consult your car's repair manual. Keep in mind that on some vehicles, the oxygen sensors may be difficult to reach without the equipment available in professional service bays. If this applies to your car, take it to your local mechanic instead. Check service costs at several local Atlanta mechanics, and plan to pay between $200 and $300 for the replacement, depending on the make and model of your car.
With a new oxygen sensor, you will be ready to hit the road again, and you can be confident that you are getting the best possible fuel economy from your car.