An O2 sensor, also known as an oxygen sensor, plays a crucial role in your vehicle’s engine performance and fuel efficiency. If your sensor is faulty or not functioning correctly, it can lead to decreased performance and increased emissions. Looking for ways on how to replace O2 sensor? With some know-how with DriveRevolve, you can swap out your old one in no time.

What Is An Oxygen Sensor? What Does Oxygen Sensor Do?

No wonder the oxygen sensor or transmission speed sensor boasts significant importance in your car system. 

The O2 sensor, a so-called oxygen sensor, keeps track of the amount of unburned oxygen in the exhaust as it leaves your vehicle’s engine. Where is the o2 sensor located? In some cases, both are before your catalytic converter. Analyzing data from both sides of the catalytic converter provides insight to the computer on its functioning and identifies any potential issues with your emission system.

By constantly monitoring oxygen levels and relaying this info to your engine’s computer, these sensors inform your car whether the fuel mixture is running too rich (insufficient oxygen) or too lean (excessive oxygen). Maintaining a proper air-fuel ratio is crucial for a car’s flawless function.

What Is An Oxygen Sensor?
The O2 sensor. Source: thevehiclelab

How To Replace O2 Sensor?

Check this video in advance: How to Check and Replace an Oxygen Sensor (Air Fuel Ratio Sensor) – YouTube

Diagnose Lousy Oxygen Sensors

Each car has at least two oxygen sensors, and possibly more, case-by-case. With FIXD’s Live Gauges feature, you can monitor the real-time data these sensors provide. 

In the scenario presented here, sensor 1 exhibits normal fluctuations as expected, while sensor 2 consistently reads 0 volts. In other cases, there is an issue with both. 

It’s high time for thorough research to ensure no underlying problems with the sensor. If all other aspects function correctly, you can presumably conclude that a faulty sensor needs changing soon.

Unplug Your Sensor

Disconnect the oxygen sensor from its wiring connection. Extracting it from the exhaust pipe will enable it to rotate without hindrance.

Lubricate Your Threads

The oxygen sensor is threaded like a screw or spark plug into the exhaust pipe. The metal undergoes repeated contraction and expansion cycles due to cooling and heating, ending with a snug fit for the sensor. 

Rust is also a common issue in this area, exacerbating the problem. To facilitate removal, apply penetrating oil such as WD40 or PB Blaster to the area and allow it some time to work its way in. 

Dismantle Your Sensor

In case of a lack of room, adopt an open-end wrench or oxygen sensor socket for the removal. The particular socket contains a slit through which the wire can pass, enabling it to slide down over the sensor. 

Your socket wrench or extension connects to an offset flange to enhance leverage. Afterward, extract the old sensor from its position.

Install Your New Sensor

Before performing the new one’s installation, read the manual sparingly for doing the opposite of removing. Tighten the new sensor securely into the exhaust pipe and connect it to the wiring harness.

Clear Your Codes

Scan your trouble codes again using FIXD, and tap the Clear Engine Light button at the bottom of the screen. This will efficiently erase all the codes and deactivate the check engine light.

Try For A Drive

Crank up your car to check if the check engine light stays off, signifying that you let off the issue entirely. If the light comes back on, the sensor you replaced wasn’t actually causing the problem. As such, rely on FIXD to read error codes and further investigate the issue.

Try For A Drive
Go for a drive after the replacement. Source: pressablecdn

Is It Safe For Driving With A Faulty Oxygen Sensor?

No. Driving with a faulty oxygen sensor can result in rough engine performance, potential power loss, or even damage to the engine itself. Also, if you reside in an area where emissions tests are part of car inspections, you may fail the engine light checking.

Several diagnostic trouble codes (DTCs) can appear when an oxygen sensor malfunctions. In most cases, a defective oxygen sensor triggers the check engine light and generates a fault code that can be read using an OBD2 scanner like FIXD. This fault code will indicate the nature of the failure and guide further diagnostic procedures.

Deciding whether to replace an oxygen sensor on your own or take it to a repair shop depends on how accessible the sensor is. Replacing my van’s sensors is simple as they can be easily reached by removing the “doghouse” at the engine’s back. Still, for other autos, accessing the sensor may require navigating tight spaces between exhaust pipes and car floors or significant dismantling of exhaust systems. If this proves too challenging for you, go for a professional handle.

When Should You Replace The O2 Sensor?   

Only change them when they malfunction or get damaged. Some indicators suggest an urgent change or temporary fix for a bad O2 sensor.

– Your check engine light is on

– A noticeable increase in fuel consumption

– Difficulty starting the vehicle

– Rough idling

– Possible misfiring of spark plugs

– Dropped acceleration performance

– The presence of black smoke from the exhaust pipe 

– A rotten egg or sulfur-like odor from your exhaust

When Should You Replace The O2 Sensor?
The rusted sensor needs upkeep at once. Source: offroadingpro


Will Changing O2 Sensor Improve Performance?

Yes. Replacing high mileage O2 sensors before they fail may enhance fuel efficiency, lower emissions, and hinder aggravating driveability hassles. 

How Long Should O2 Sensors Last?

The typical lifespan of an oxygen (O2) sensor is roughly 30,000 – 50,000 miles. Cutting-edge versions can operate up to 100,000 miles without upkeep or replacement.

Should O2 Sensors Be Replaced In Pairs?

Yes. It is best to replace your O2 sensors in pairs.


There you have it – the process on how to replace O2 sensor. Whether you’re a seasoned mechanic or a novice DIYer, we got you covered. A faulty O2 sensor can lead to decreased fuel efficiency and increased emissions, so tackling the issue promptly is core. 

Many good reads for Fun Autopart may pique your interest a lot!

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