If your vehicle’s engine is running a little rough and the check engine light on the car’s dashboard flashes off and on and then stays on, it could have a bad oxygen sensor. In some cases, the vehicle may seem to idle fine with the check engine light on, but in fact, an oxygen sensor still could be the problem.
Most vehicles built within the last 25 years or so have at least one oxygen sensor and most built since 1996 have two or more. Some newer high-performance engines have an oxygen sensor for each cylinder, which could translate to as many as ten oxygen sensors. In this case, several may need to be replaced at one time.
The oxygen sensor is part of the exhaust system and is designed to monitor the amount of oxygen in the exhaust. This helps to manage the efficient operation of the engine. A bad sensor left unchanged can lead to lower gas mileage, pollution and other car problems down the road.
Start with a Diagnostic Test
While there are several problems that could cause a check engine light to come on, the oxygen sensor is at the top of the list. But to know this for certain, it is necessary to get a engine diagnostic test. You can take their vehicle to a dealer or repair shop and pay anywhere from $50 to over $100 for a diagnostic test, depending on the shop and the car. However, some auto parts stores, such as AutoZone, want people to buy from their store, so they may offer a free diagnostic test.
Once the correct problem has been determined to definitely be an oxygen sensor and you have identified the appropriate one to be changed, you can either buy the part from a local parts store or order from an online discount company, such as RockAuto.com. Prices for oxygen sensors can range from $20 to over $100 each, but car owners can save a bundle on labor and part markups by doing it themselves.
Replacing the Sensor
To replace a worn out oxygen sensor, you may want to check the owner’s repair manual and see exactly where the part is located. Most engines have two sensors, one located before and one after the catalytic converter. If the car has several sensors, more than one may need to be replaced, depending on the diagnostic test results.
No special tools are required to remove your old oxygen sensor unless it is stuck on or out of reach and then it may be helpful to use pliers. Simply grab and pull out the old part and insert the new part. Some engines may be crowded making this process a little more difficult, but usually can be removed with some extra effort. It is helpful to use zinc oxide ointment on the inserted end of the new oxygen sensor to make it easier to remove the next time it needs to be replaced.
After the new oxygen sensor has been changed, it is time to start the vehicle. It may take a few starts for the check engine light to go off. If it doesn’t go off after a few starts, you can return to the place where the diagnostic test was done and ask them to shut off the light manually or test for another problem.
Once the oxygen sensor is installed, depending on the make/model of the vehicle and the miles on it, the engine should be purring along for another 30,000 miles or so before it needs to be replaced. However, if only one sensor was replaced, the others may not be far behind in needing to be changed as one bad sensor can lead to another.