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Types of Oxygen Sensors
There are a few different types of oxygen sensors commonly used in modern vehicles, which include heated, unheated, upstream, and downstream sensors.
Heated Oxygen Sensors
The most common type of oxygen sensor is the heated oxygen sensor. As the name suggests, this sensor features a built-in heating element that allows it to quickly reach and maintain its operating temperature. By doing so, it can accurately measure the oxygen content in the exhaust gas, which is compared to the outside air to determine the air/fuel mixture.
Unheated Oxygen Sensors
Unheated oxygen sensors, as the name suggests, do not have a built-in heating element. Instead, they rely on the hot exhaust gases to bring them up to operating temperature. Unheated oxygen sensors are typically found on older vehicles or on vehicles with lean-burn engines, such as diesel engines.
Upstream Oxygen Sensors
Upstream oxygen sensors measure the oxygen content of the exhaust gas before it enters the catalytic converter. By doing so, it provides valuable information regarding the air/fuel mixture in the raw exhaust gases and allows the vehicle’s computer to adjust accordingly. Upstream oxygen sensors are typically located on the exhaust manifold or just before the catalytic converter and are usually heated sensors.
Downstream Oxygen Sensors
Downstream oxygen sensors are typically found downstream of the catalytic converter and provide a secondary reading of the oxygen content of the exhaust gas. It allows the vehicle’s computer to monitor how effective the catalytic converter is in reducing harmful emissions. Downstream oxygen sensors are usually unheated.
When to Replace an Oxygen Sensor
A faulty or malfunctioning sensor can lead to a variety of issues with your vehicle. It’s important to be aware of the symptoms of a bad oxygen sensor so that you can have it replaced as soon as possible. Here are some common signs that your oxygen sensor may need to be replaced:
- Check Engine Light. One of the most common indications of a bad oxygen sensor is when the Check Engine Light on your dashboard turns on, and it can be for a variety of issues.
- Reduced fuel efficiency. A bad oxygen sensor can cause your engine to run rich, which means that it’s consuming more fuel than it needs to. Not only will this reduce your fuel efficiency, but it will also increase your emissions and cause your vehicle to produce more pollution.
- Rough idle. If you notice that your engine is idling roughly or stalling frequently, it could be due to a bad oxygen sensor because the incorrect air/fuel mix can cause your engine to misfire or run poorly.
- Poor performance. A bad oxygen sensor can also lead to poor engine performance, including sluggish acceleration and reduced power. This is because the engine is not receiving the correct air/fuel mix, which can cause it to work harder than it needs to.
It’s important to deal with a bad oxygen sensor quickly, otherwise, it has the potential to cause damage to other parts like the catalytic converter, adding more time and cost.
How to Replace an Oxygen Sensor
Replacing an oxygen sensor may sound like a complicated task, but with the right tools and a bit of know-how, it’s a job that almost anyone can do in their own garage. Here are the general steps for replacing an oxygen sensor.
1. Locate the oxygen sensor
The first step is to locate the oxygen sensor you need to replace. Most modern vehicles have at least two oxygen sensors, one upstream and one downstream of the catalytic converter. Be sure to doublecheck that you have the right one.
2. Remove the old oxygen sensor
Once you’ve located the oxygen sensor, you’ll need to remove it. This can be the most challenging part of the job, as oxygen sensors can become corroded and difficult to remove. You should use a wrench or a specialized oxygen sensor socket to remove the sensor. Be careful not to damage the sensor’s wiring during removal.
3. Install the new oxygen sensor
With the old oxygen sensor removed, it’s time to install the new one. Take care to install the new sensor in exactly the same location and orientation as the old one. You should tighten the new oxygen sensor to the manufacturer’s recommended torque settings.
4. Reconnect the wiring
Once the new oxygen sensor is in place, reconnect the wiring. Make sure the connections are tight and secure, and that the wiring is routed correctly.
5. Clear the trouble code
After installing the new oxygen sensor, you’ll need to clear the trouble code. You can do this by disconnecting the battery for a few minutes or using a scan tool. This will reset the vehicle’s computer and allow it to start collecting new data from the new oxygen sensor.
If you still have a trouble code related to the oxygen sensor after the repair, it’s possible there’s another problem, and it could be causing readings out of the normal range. Additional diagnosis will be necessary to trace the symptoms to the root.
Need a new oxygen sensor for your car? Your local AutoZone carries a fantastic selection from reputed brands in the industry. And if you decide that it’s too big a job to tackle on your own, let AutoZone help you find qualified professional mechanics through our Shop Referral Program.
FAQ/People Also Ask
What happens if I don’t replace my oxygen sensor?
Usually, your Check Engine Light will remain on until it’s fixed. Also, it can cause emissions-related problems, you’ll fail a smog check, and you’ll burn more fuel than necessary in many instances.
How long does it take to replace an oxygen sensor?
It depends on your skill level and the complexity of your vehicle’s design. Allot an hour or two per oxygen sensor.
Can a bad oxygen sensor cause a check engine light?
Yes, definitely. If the oxygen sensor’s readings are outside of the normal range, it will trigger a Check Engine Light.
How much does it cost to replace an oxygen sensor?
It varies greatly depending on the car. It could be from under $40 for just the sensor to more than $400 for parts and labor together.
Can I replace an oxygen sensor myself?
It’s possible, yes. With common tools and a bit of time, you can change your own oxygen sensors. If you aren’t comfortable, bring it to a mechanic to get the job done.
