Oxygen Sensor Replacement Guide - How to Replace an O2 Sensor

The oxygen sensor is one of many sensors in your car's engine management system. All cars built since the early 1980s have at least one, some have two or more. If an oxygen sensor malfunction, so your car's performance and fuel economy will decline and it will generate excessive hydrocarbon emissions. A failed sensor can also damage the catalytic converter, a costly emission system component. Replacing the oxygen sensor at recommended intervals or when it is failed will keep your engine running at the correct calibration, for best power and economy, and save you money in the long run. Protecting the environment while saving money is a good thing. So, we're going to look at how to diagnose and replace an oxygen sensor right here, right now. Welcome to the AutoZone DIY Garage. The oxygen sensor helps the vehicle's engine management computer determine correct fuel mixture by measuring the amount of oxygen in the exhaust. A lot of oxygen indicates the engine is not getting enough fuel to burn. Very little oxygen in the exhaust means that the engine is getting too much fuel. When the computer gets a signal from the oxygen sensor, it adjusts the air fuel-mixture to compensate, there by maintaining a near perfect ratio. If the computer doesn't get a signal from the sensor, the car won't stop, but it will not operate at peak performance or efficiency. Did you know a car with a malfunctioning oxygen sensor may seem okay, but it will waste fuel while spewing greenhouse gases and other pollutants into the atmosphere? Because oxygen sensors live in a harsh environment, they should be replaced at recommended intervals even if they haven't failed. Sensors connected to the wiring harness with one and two wires should be replaced at 25,000 to 30,000 miles. Three or four wire sensors have a life expectancy of about 55,000 to 60,000 miles. Some four wire sensors can last up to 100,000 miles, while senors with five or six connecting wires are rated at 150,000 miles. Most cars built between 1980 and 1996 have one oxygen sensor located between the exhaust manifold and the catalytic converter. If your car is of that period and symptoms like excessive fueled use, lack of power and illuminated check engine light suggest the oxygen sensors failed, it wouldn't hurt to replace it. Maintenance replacement is probably overdue and the job isn't difficult. Most cars built after 1996 have at least two sensors. If the check engine light switch is on in a car built after that date, you can determine if a failed oxygen sensor is the culprit by reading trouble codes set in onboard diagnostic system with a code reader. This tool which is available at auto zone will tell you which sensor has failed and because industry specifications for engine management diagnostics were standardized in 1996, it will work in almost any later model car. But, read the operating manual before attempting to use it. To read the codes on the Ford Fusion, simply plug the code reader into the data link connector here on the driver's side. If the car had a failed sensor, the code reader would indicate which sensor had failed and where it was located. It would tell you if the culprit was sensor one, which is always upstream of the catalytic converter or sensor two, which is always behind the converter. For V6 V8 cars, which can have as many as four oxygen sensors, the code reader would indicate if the defective sensor was in engine bank one or bank two. Most vehicles have an oxygen sensor froward of the catalytic converter, and another one behind the converter. Here, we'll use a section of exhausts that holds an oxygen sensor to show you how easy it is to install a new unit using the right tools. Once you've determined which sensor is defective, you can remove it with his special oxygen sensor socket wrench, which is available at AutoZone. Because the sensor corrodes with the exhaust system, it can be tough to loosen, so squirts and penetrating oil on the threads before attempting removal. After attaching the socket to a three-eighths drive ratchet, place it over the sensor and turn counterclockwise to remove it, being careful not to damage the wires. To install the new sensor, remove the plastic cover and if the threads are not already coated with anti-seize compound, apply some, but be careful to apply it only to the threads. Contaminating the tip of the sensor can affect its performance. You should also make sure it doesn't bump up against the pipe when inserting it into the sensor mounting hole. After screwing the sensor down by hand, tighten it to manufacturer specs with the oxygen sensor socket mounted on a torque wrench. Then, reattach the wiring and make sure it's routed away from the exhaust. As you're seen, replacing an oxygen sensor isn't difficult, and it's a job you shouldn't put off because a defective sensor will cause your car to run poorly while spewing pollutants into the atmosphere. For more details about oxygen sensor replacement or any other automotive surface topic, be sure to talk to the experts at AutoZone. Remember, parts are just part of what we do.


ACDelco Exact Fit Oxygen Sensor AFS105
Bosch Exact Fit Oxygen Sensor 15510
Denso Universal Fit Oxygen Sensor 234-4209