What Causes An Oxygen Sensor To Fail Or Go Bad: 7 Reasons – O2 Sensor Failures & Replacement Tips

What Causes An Oxygen Sensor To Fail

An oxygen sensor also called O2 Sensor or lambda sensor (λ) is an important component of engine management that detects how much oxygen left unburnt in the exhaust manifold after combustion.

he oxygen sensor is located in the exhaust manifold before and after the catalytic converter. The oxygen sensor located after the catalytic converter is called the downstream oxygen sensor, while the oxygen sensor located before the catalytic converter is called the upstream oxygen sensor. The exhaust gases can carry, oil, grease, carbon, pollutants, etc, whose deposition is a sign that your O2 sensor is faulty.

Fortunately, this whole page is about the causes of oxygen sensor failure. In this powerful guide, you will quickly learn what causes an oxygen sensor to fail.

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What Causes An Oxygen Sensor To Fail Or Go Bad

Bad Oxygen Sensor Symptoms
Bad Oxygen Sensor Symptoms

Multiple reasons can cause the oxygen sensor to fail. Sometimes, Oxygen sensors get clogged and contaminated due to the byproducts of the fuel.

When a sensor gets failed, it does not provide the correct data to the ECU, and the car gives several problems. Here below is the seven reasons, which are major causes of failure. Avoid it not to damage your car.

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7 Reasons Why Oxygen Sensor Fails

1. Time Kills

Killing Time Concept
Killing Time Concept

Time is one of the most common cause, which causes failure. The life span of the oxygen sensor is 3 to 5 years or 60,000 to 90,000 miles.

Over time, like every part in the car wears out, the same is true for them, it wears out with time, which affects the oxygen sensor’s response characteristics, resulting in a failed sensor.

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2. Contamination

Contaminated Oxygen Sensor
Contaminated Oxygen Sensor

Contamination is another big reason, which causes oxygen to fail. The oxygen sensor may become contaminated with many byproducts of fuel, such as lead, sulfur, and fuel additives

This contamination of byproducts stops the sensor from sending the right signal to the ECU as a result, the oxygen sensor goes bad, needs to be replaced with the new oxygen sensor

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3. High Temperature

Overheated Engine
Overheated Engine

These oxygen sensors become faulty due to high temperatures. In general, high exhaust gas temperatures make your oxygen sensor faulty

This extremely high temperature quickly reduces the lifespan, and as a result, the O2 sensor dies.

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4. Not Doing Regular Maintenance

Car Repair And Service
Car Repair And Service

There is a saying, if you are not growing, you are dying. It means, if you want to maintain something, you have to grow it, otherwise, that thing will slowly die. Similarly, if you want your vehicle to run properly, you have to take care of it, I mean you have to do regular check-ups.

A good working oxygen sensor helps to reduce fuel usage by as much as 40%. The old sensor will increase the amount of unburnt gases. These components will also fail faster due to a dirty air intake filter and a fouled spark plug

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5. Using Low-Quality Gasoline

Lack Of Money Ends Up Buying A Low Quality Gasoline
Lack Of Money Ends Up Buying A Low-Quality Gasoline

Lack Of Money Ends Up Buying A Low-Quality Gasoline Low-quality gasoline is also a big cause of failing oxygen sensors. Fuel, which is not recommended for your vehicle or low-quality fuel can reduce their average life. It is because low-quality gasoline can produce more sulfur, lead, and oil ashes, which makes the oxygen sensor coated with it.

6. A Leaky Gasket

Worn-Out Gasket
Worn-Out Gasket

A leaky gasket can also cause failure. A leaky head gasket can produce silicate, which blocks the oxygen sensor, keep your sensor from sending signals and create the illusion that sensor is bad.

This is an Info
The instrument which measures unburnt oxygen can be contaminated with various exhaust byproducts including silicates from an internal engine coolant leak.

Related Post: Can Water Damage The Oxygen Sensor?

7. A Worn-Out Piston Rings

Worn-Out Piston Rings
Worn-Out Piston Rings

An oxygen sensor can become faulty due to worn-out piston rings. Worn-out piston rings, valve guides, or cracks in the cylinder block and combustion chamber produce phosphorous from the engine oil, which causes to fail the oxygen sensor to.


One thing I want to share with you is that whenever the oxygen sensor fails, try to figure out the exact cause behind the failure. Just changing the oxygen sensor without targeting the underlying problems will again fail it.

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What Are The Issues A Bad Oxygen Sensor May Cause?

The oxygen sensor is an important component that measures the amount of oxygen present in exhaust gases. A faulty component causes a variety of issues with a vehicle’s performance. Some of the most common problems include:

  • Poor fuel economy: A faulty sensor negatively affects the engine by using fuel that isn’t recommended for your vehicle like running on a lean mixture (mixture without enough fuel) or rich fuel mixture (too much fuel, not enough air) which indicates that for poor fuel economy sometimes sensor is the issue.
  • Decreased engine performance: A defect in the oxygen sensor of a car affects optimal engine performance by creating a misfire or run poorly, due to which the vehicle experiences problems like a decrease in power and acceleration.
  • Increased emissions: A faulty sensor can cause the engine to burn fuel inefficiently, leading to an increased amount of oxygen present in the exhaust.
  • Trigger The Check Engine Light: A faulty sensor signals the “Check Engine” light on the dashboard, alerting the driver to a potential problem with the car

It is important to address any issues caused by the oxygen sensor in your vehicle as soon as possible to avoid further damage to the car and to ensure that it’s working properly.

Can I Drive With a Failing O2 Sensor?

Contaminated Oxygen Sensor
Contaminated Oxygen Sensor

While it may be possible to drive a short distance with a bad sensor, it is not a good idea to continue driving if the O2 sensor fails because it is continuously affecting oxygen levels in the exhaust. If an oxygen sensor becomes caked with byproducts of combustion, it may not be able to accurately measure the oxygen content of the exhaust gas. You must replace an oxygen sensor with a new o2 sensor.

A poor condition of the sensor can cause problems with the engine’s performance and fuel efficiency by using the wrong ratio of fuel mixture, which will also increase emissions. A faulty sensor becomes dangerous for the vehicle and may even render it undrivable.

It is best to replace a bad sensor in your vehicle if the sensor is failing to avoid any potential issues and to ensure the proper functioning of the vehicle

When Should You Replace An Oxygen Sensor?

Rear Oxygen Sensors On Dual Exhaust System
Rear Oxygen Sensors On Dual Exhaust System

There are a few signs that you may need to replace your oxygen sensor.

  • Your vehicle’s emission levels are higher than normal: If its emissions test shows that emission levels are higher than usual, it may be a sign that your oxygen sensor is not functioning properly. The oxygen sensor is responsible for measuring the amount of oxygen content in the exhaust, so if it fails, it can result in higher emission levels.
  • Your fuel economy is worse than normal: A bad oxygen sensor can also affect the amount of fuel consumed by your car. If your gas mileage is worse than usual, it may be a sign that your oxygen sensor needs to be replaced.
  • Your check engine light is on: If your check engine light is on, it may be a sign that your oxygen sensor is not functioning correctly. You can use a diagnostic tool to retrieve the fault code by facing such symptoms of a bad oxygen sensor.
  • Your air filter or catalytic converter needs to be replaced: If your vehicle needs air filter replacement, it may be a good idea to also replace the oxygen sensor at the same time when the vehicle is checked by an electrician. These components often fail together due to the high levels of heat and oxygen in the exhaust system

In general, it is a good idea to replace your oxygen sensor every 60,000 to 90,000 miles. This will help ensure that your vehicle’s emission levels are within the normal range and that your fuel consumption is not increased by a faulty oxygen sensor. If you suspect that your oxygen sensor may be faulty, it is recommended that your vehicle be checked by a mechanic as soon as possible to avoid further damage to your car.

Oxygen Sensor Replacement Tips

Here are a few tips to keep in mind when replacing an oxygen sensor:

  • Make sure to use the correct type of sensor for your car. A wrong sensor will affect the exhaust stream by providing inaccurate data about oxygen levels in the exhaust.
  • Follow the instructions provided with the new sensor carefully to ensure proper installation.
  • Use a torque wrench to tighten the sensor to the correct torque specification.
  • If you are having difficulty accessing the sensor, try using an o2 socket or extension bar to reach it.
  • If you are not comfortable performing the replacement yourself, it is always a good idea to have your vehicle checked by a professional electrician. Frequently Asked Questions (FAQs)How Long Does an Oxygen Sensor Last?

Frequently Asked Questions (FAQs)

How Long Does an Oxygen Sensor Last?

The average oxygen sensor of your car will last anywhere from 30,000 to 50,000 miles. However, there are a number of factors that can affect the lifespan of an oxygen sensor. These include the quality of the sensor, the make and model of your vehicle in which it is installed, and the driving habits of the driver.

How to Prolong Oxygen Sensor Life?

In order to prolong the life of your oxygen sensor, it is important to follow a few simple tips. First, make sure that your vehicle is running on clean fuel which will keep your car running smoothly. This means using fuel that is free of contaminants and impurities. Second, keep your engine tuned up. This will help to reduce the number of harmful emissions which are produced. In the end, modern cars have their own schedule for replacing sensors so check them accordingly.

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