Oxygen sensors are fairly new in terms of how cars are constructed relative to automaking as a whole. It was only in 1996 that all vehicles were required to have an oxygen sensor included upstream and downstream of the catalytic converters. If your oxygen sensor fails that means you need a replacement and you're looking at a repair cost of about $250 to $500 depending on where you go.
If you head to AutoZone right now you'll see that most O2 sensors cost between $50 and $250 just for the part brand new. The differences of course are going to be labour costs, and the process of replacing one will take about an hour or so.
As with nearly any repair job, the labor costs will greatly increase the overall cost of getting the part replaced. The problem is that repairs are never consistent from one mechanic to another, as well as one make and model of vehicle to another. The kind of vehicle you're driving and where you take your car will always have an effect on how much you pay at the end of the day. Your best bet is always to either go with a mechanic you’ve trusted for years or, if this is new to you, make sure you’ve researched thoroughly online to find out who's going to be best in your area.
These days, nearly every mechanic you can find will have a number of reviews on the internet. Even though some people who have bad experiences can try to skew the results, for the most part you'll be able to get a feel for the quality of service you get from a mechanic by reading over some of the reviews and checking out what their average score is. Google reviews and Yelp are great for this kind of thing and it could really help you determine who's going to give you the best deal for replacing a faulty oxygen sensor.
What is a Car Oxygen Sensor?
Oxygen sensors are typically known by a couple of different names in cars. You'll often see them referred to simply as O2 sensors, but they are sometimes also known as lambda sensors. Though they didn't become standard in every car until the mid-1990s, they were developed as far back as the 1960s. The purpose of an oxygen sensor is, as the name suggests, to measure the amount of oxygen in a given liquid or gas.
Older oxygen sensors were made with heavy ceramics coated in platinum but it was the one developed in the 90s, known as planar-style, that significantly reduced the size and weight and made them a lot cheaper as well.
An O2 sensor is able to measure whether or not your fuel to air ratio is lean or rich. They're part of the exhaust system of your car however the information gathered by the oxygen sensor is used to help calibrate your fuel injection and emission control to ensure that the precise amount of fuel and air are being burned in the combustion chamber of your vehicle. It's a loop system that constantly monitors everything from the beginning to the end of the combustion process to ensure that you're burning fuel as optimally as possible.
As you can see, while it may not seem at first that the O2 sensor is integral to how your car operates, just monitoring the exhaust fumes of your vehicle, it's actually an important part of how the engine runs. That will reflect on how much you pay for fuel overall as well as how efficiently your car performs.
The second function of the O2 sensor is that it monitors output from your vehicle, which means that part of its overall function is to reduce the dangerous chemicals that are pushed out through your exhaust. Through the constant monitoring of the oxygen sensor as well as the other sensors in your engine and fuel system, you burn fuel more efficiently and more cleanly. O2 sensors are therefore one of the few parts of your vehicle that helps you out as a driver, but also helps everyone else out at the same time by trying to reduce emissions and making the world a bit of a cleaner place.
Signs of a Bad Oxygen Sensor
When your oxygen sensor starts going bad there are a few telltale signs you can look for to let you know what's going on. As with many issues that can plague a car, these problems could also be indicative of something else, but this will help you narrow the field down to how oxygen sensors fail, and give you some insight so you can help a mechanic properly diagnose whatever might be wrong with your vehicle.
- Check Engine Light Comes On: To be fair, you could probably list over 100 problems that will make the check engine light come on your car. But almost without fail a fuel or oxygen sensor is no longer functioning properly this is the first thing that will happen.
Anytime a check engine light pops up on your dashboard you would do well to get to a mechanic as soon as you can so they could run a quick diagnostic of your vehicle and nail down what the problem is. It could be an oxygen sensor, or it could be any number of other things, but you won't know until you get it checked out. That's the point of the light coming on, to let you know something needs to be looked at before it goes from a small problem to a big one.
- Poor Engine Performance: Because your oxygen sensor is integral in determining the fuel/oxygen ratio, if it's not working correctly then your car may not be burning fuel correctly. That in turn can cause your engine to underperform significantly. If you're finding that when you put your foot down on the gas, you're getting very little pick up at all and acceleration is difficult or much less than You're Expecting, there is a chance that your oxygen sensor could be the culprit.
- Bad Fuel Economy: The oxygen sensor helps determine how much oxygen and how much fuel needs to be injected into the combustion chamber to power your vehicle. If the sensor is not functioning properly, you could be experiencing a rich fuel mixture which pumps too much gasoline into the chamber. Not only this is how the potential of ruining your engine, it's also going to be extremely costly at the pumps as you'll be going through gasoline much faster than you normally would if everything was working the way it was supposed to. This is one of the first and most noticeable ways to determine that there is something wrong with the oxygen sensor how's your vehicle. You'll just find yourself feeling out for way more often than you think is normal.
- Rough Idling: When you're parked and your car not moving with the engine running, your RPMs should be under 1000. If when you're at a standstill and you see it bounce up to 2,000 or more for no reason whatsoever, or if you are experiencing random misfires and unusual noises, then your car is having an issue with rough idling. This could be caused by the oxygen sensor being off and your car engine burning fuel in consistently as a result.
- Bad Emission Test Results: This is a less common symptom of an O2 sensor working improperly because not everyone on the road is going to have to go in for an emissions test. Some states don't require them, and some model vehicles don't have to get them done. But if you do have to take an emissions test for your vehicle and you fail because your emissions are not within the expected guidelines, it's a possibility that your O2 sensor has failed and that's the cause of it.
Can I Replace My Own Oxygen Sensor?
Replacing your car's oxygen sensor is not as difficult a job as many repairs can be. If you're not 100% confident working under the hood of the car, and you're not familiar with this particular repair, you may be better served by finding a mechanic to get the job done for you.
That said, if you think you can handle the job it's not overly complicated and there are a number of guides you can find online to walk you through the process. There are also numerous videos you can find on YouTube that can show you step-by-step what to do in real time, which some people find easier to follow along with it when it comes to a repair like this.
If you do believe that your oxygen sensor has failed you just need to make sure you have it properly diagnosed first before you take the time to remove one from your car and swap it out with a new one. Since the symptoms of a failed O2 sensor are so similar to issues that can be caused by many other problems, you want to use an OBD code scanner to figure out for certain if the problem with your car is in fact that oxygen sensor. Mechanics use these tools frequently to diagnose problems, but you can also get your own fairly cheaply on a site like Amazon. While some OBD2 scanners cost upwards of $100, you can get some that cost under $30. If you're serious about DIY car repair, then it's well worth investing and one so you can keep an eye on what's wrong with your vehicle.
Even with the cost of an OBD scanner factored in, it's possible you could save yourself $100 or $200 by performing this repair yourself.
If you know for sure that the problem is the oxygen sensor then It's best to leave this one to a professional and get it properly diagnosed by a mechanic.
What Happens If I Don't Replace My Car's Oxygen Sensor?
The longer that you wait to replace a broken O2 sensor, the worse the problems can get over time. While at first it may not seem like a big deal to have your check engine light illuminated and some rough idling in your vehicle, the problem will get worse. If your fuel to air ratio gets skewed too badly you will be constantly burning fuel at an incorrect ratio. That could cost you a lot of money over time because you're burning too much gas.
Another issue with not replacing your O2 sensor when it malfunctions is that, with this incorrect fuel to air ratio burning in your engine, you could end up burning extremely hot. This can burn out the catalytic converters over time and cause severe engine damage. For the cost of a $100 oxygen sensor, you might end up having some serious engine repair bills to deal with.
Overheating in the engine can end up causing a lot of serious damage. Engine repair bills can stack up to well over $1,000 if the problem is severe enough, sometimes as much as $2,000 and $3,000.
The other concern with not getting your oxygen sensor repaired right away is that you're facing an issue with your emissions as well. If you are concerned with the environment as we all should be, then you don't want to be belching any more damaging fumes into the atmosphere that is entirely necessary.
The Bottom Line
Replacing your faulty oxygen sensor is something that you should definitely take care of as soon as you're aware that it's a problem. The longer this is left to go, the worse the problem will be.
A lot of times, a faulty oxygen sensor will be left by the wayside because your car can function quite well without it being repaired for a while, and the symptoms that it presents are often confused for other issues. That means some drivers are tempted to backburner this problem, but it's really in your best interests to get it done quickly so that you can save yourself money and hassle down the road by letting it go for too long.