7 Signs of a Bad Oxygen Sensor (Causes & Fixes)

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If you want to keep your vehicle as healthy as a horse, you need to ensure the upkeep of its oxygen sensor. People often wonder if tiny components have a small or insignificant role in the overall vehicle's performance. But that doesn't seem to be the case. O2 sensors keep the exhaust system's oxygen levels in check and ensure a more efficient and clean engine. Emission tests are one of the ways of telling that your car's oxygen sensor is going bad. But, numerous other symptoms can help you identify a bad O2 sensor. You can identify these symptoms and fix the problem before your car runs into engine troubles and poor fuel combustion. Below is a discussion of all the common symptoms of a bad oxygen sensor. Keep reading! How Does an Oxygen Sensor Work? It is essential to understand how this tiny device works before we jump to the symptoms. The size of an oxygen sensor is similar to that of a spark plug. The purpose of the oxygen sensor is to keep track of the amount of oxygen in the exhaust. The sensor keeps track of how much oxygen is present in the exhaust and compares the results to outside oxygen levels. The sensors forward the results to your car's system for processing and further adjustments. Post this, the car’s engine system will adjust the ratio. The ultimate goal of this process is to help your car run efficiently. Also, O2 sensors work towards preventing toxic emissions and improving gas mileage. Modern vehicles have computerized engines that include sensors to regulate and enhance overall performance. As the vehicle's engine system gathers this information, it adjusts the ratio of oxygen to fuel in the engine. It is an endless loop where the sensors track the oxygen levels in the exhaust and send the readings to the car's engine system. When your car's O2 sensors malfunction or break, the engine system will inject a rich blend of fuel. When this situation takes place, it’ll increase the fuel consumption of your car. Besides, it’ll also increase the production of carbon in the car. exhaust manifold Image Credits: Oxygen Sensors in Cars What Are the 7 Symptoms of a Bad Oxygen Sensor? If something is off with your car's oxygen sensor, the internal combustion system will suffer. Your vehicle will be battling with all sorts of engine drama if it has a bad oxygen sensor. Luckily, most of these symptoms are easy to spot. Here are the seven signs of a failing oxygen sensor you need to watch out for: Check Engine Light Blinking Blinking engine light is one of the most common symptoms of a failing oxygen sensor. The flashing check engine light indirectly tells you that it's time to visit the mechanic for a checkup. These sensors can impact fuel and air combustion. If the oxygen sensors find that there is less oxygen post-combustion from the exhaust gases, the engine will keep trying to adjust it. Unfortunately, if the oxygen sensor is malfunctioning, the engine system can overlook such problems. Ultimately, it'll lead your car to poor vehicle performance. The car’s engine module will also understand that there is a problem with the engine. Also, this situation can trigger the check engine light. In high-end cars with built-in engine systems, you may spot error codes. The code generally indicates that the O2 sensor is malfunctioning. Poor Fuel Economy If your car has been suffering from poor fuel economy, the chances are that the oxygen sensor is not working as it should. When your vehicle is consuming fuel abnormally, it's time to replace the oxygen sensor. Whenever the fuel in the engine is too lean or rich, the fuel combustion efficiency reduces. Since the oxygen sensors degrade with time, it gives wrong signals to the systems and you'd notice fuel consumption amount spiking. Your car will burn more fuel than expected which is a sign of poor fuel economy. For this reason, an O2 sensor is an integral part of the vehicle. Rough Idling Engine and Misfires When the car's oxygen sensors are not working appropriately, it will frequently run roughly and misfire while idling. A bad oxygen sensor comes with several other engine problems, such as engine hesitation, stalling, and power loss. As you would have read before, the sensor is responsible for sending information to the car’s engine system. This data helps in combustion intervals and engine timing. In turn, these affect the air to fuel ratio that translates to efficiency in combustion. In a nutshell, a poorly working oxygen sensor disturbs the engine system and leads to irregular and rough engine functioning when idle. Deteriorated Engine Performance You can save a lot on automotive repair bills if you spot a lousy oxygen sensor on time. Another O2 sensor failure sign is weakened engine performance. If there is an issue with the combustion process of your car's engine system, it will eventually lead to a weaker engine. You can understand poor engine performance while driving. While driving, if the acceleration seems to stumble, it is a sign of poor engine performance. Your car will not be able to deliver the same performance as before in this case. Failing Emissions Test Another symptom of failing oxygen sensors is the constant failure in emission tests. The O2 sensor is located in the manifold of the exhaust system which allows it to help with emissions control. Some of the states and counties have a rule for vehicles to pass the emission tests. These emission tests ensure that your vehicle is not producing carbon dioxide over safe levels. You might not be aware, but the oxygen sensor helps with emission control. As a result, a failed emission test is an indication that your oxygen sensor needs a look! Emission of Black Smoke Many car owners take the problem of black smoke very lightly. However, most of the time, it signifies something drastic. Black smoke is an indication of improper combustion within the car’s engine system. As you would have read above, an oxygen sensor plays a critical role in sending data to the car’s engine control unit. It tells the engine system how to adjust the fuel and air quantities. In any case, oxygen sensors work to prevent emissions. A bad oxygen sensor might not be accurately able to balance the fuel to air ratio. It means that the combustion process will be insufficient. It will ultimately result in black smoke residue. Intolerable Rotten Egg Smell Is your car lately smelling odd and weird? Naturally, you might not take it as a symptom of a car part failure. But please do know that a broken oxygen sensor could be the cause of that intolerable odor. The rotten egg smell from the faulty oxygen sensor is caused by too much fuel in the engine. Excess fuel in the engine is the primary reason behind a sulphuric smell. You might also notice a cloud of black smoke coming out of the exhaust. So, whenever you refill the gas taken, take notes of the frequency and quantity. If your car is out of gas frequently, hire a certified mechanic right away! When Should I Replace My Oxygen Sensor? If you have noticed any of the symptoms, you might be confused if you should replace your oxygen sensor or not. Like other parts of your vehicle, the oxygen sensors might also go through damage. Installing a new oxygen sensor ensures the fuel efficiency and safety of your car. If your car's manufacturing dates back to 15 years, you must replace the oxygen sensor every 60,000 to 90,000 miles. An old and deteriorating oxygen sensor might not be able to produce accurate feedback. Keeping up with the replacement schedule can help you skip failures and toxic emissions. As soon as you spot any symptom like poor gas mileage or blinking engine light, we recommend you book a checkup with a mechanic. fuel mixture Image Credits: Oxygen Sensor in Working Condition FAQs What Can Happen to a Vehicle If It Has a Failing Oxygen Sensor? When your car's oxygen sensor is not working aptly, it might send incorrect feedback to your car's PCM. In some cases, it might not send any feedback at all. These errors make it difficult for your car to balance the oxygen to fuel ratio. Proper oxygen to fuel ratio is essential for your vehicle to run smoothly. As we mentioned earlier, when your car has a bad oxygen sensor, it will experience poor fuel consumption. It might also suffer from misfiring. Can a Deteriorating O2 Sensor Lead to Power Loss? With a bad O2 sensor, it is natural to fear power loss. Since the faulty oxygen sensor sends incorrect readings, it can lead to inaccurate adjustments in the fuel system and combustion engine's intake. Such a circumstance can trigger inaccurate shifting points. Here, the blend of fuel injected by the engine will be inaccurate. Engine misfires are also a result of inaccurate shifting points. The gas mileage would also be disappointing. It is important to mention that incorrect fuel injection and fuel timing impact fuel combustion. Fuel combustion is also responsible for running your car correctly. Besides, inadequate combustion results in insufficient power for engine functions such as acceleration. Does a Bad O2 Sensor Also Cause Sputtering? The primary function of your car's oxygen sensors is to measure how lean or rich the exhaust gases are at the vehicle's combustion spot. Based on this feedback, the car balances the amount of fuel injected into the engine. A failing O2 sensor disturbs the fuel amount in the engine. As a result, your car's engine might sputter. It would help if you replaced a malfunctioning O2 sensor to restore the correct fuel to air ratio. Can I Continue to Drive My Car Even If It Has a Bad O2 Sensor? Most of the time, a bad O2 sensor does not pose any danger while driving. The possibility of the car shutting down due to a bad O2 sensor is rare. The purpose of O2 sensors is to send information to the car’s PCM to adjust the air to fuel ratio. When those sensors completely fail, the check engine lights will blink. However, you would be able to continue driving the vehicle until the O2 sensor leads to worse problems, ultimately stopping the vehicle. However, we suggest against this. What is the Cost of Replacing an Oxygen Sensor? Different factors affect the oxygen sensor replacement cost. The mechanic labor cost and car model determine the replacement costs. You might have to pay nearly $50 to $100 to install a new oxygen sensor in your car. In addition to that, the mechanic labor costs would be around $150. Rates for mechanical labor range from $50 to $150 on an hourly basis. If you have a professional mechanic, you can get the simple job done within 30 minutes. Bottom Line It would be wise to rush your car to the nearest mechanic as soon as you notice any of these symptoms. Even though you can drive a vehicle with a bad oxygen sensor, your vehicle will struggle to offer premium performance. Not only will the engine be less efficient, but you’ll also shell out more for fuel expenses. I also suggest you take your car from time to time to the best mechanic for checkups. A perfectly working oxygen sensor is suitable for your wallet and the environment!

If you want to keep your vehicle as healthy as a horse, you need to ensure the upkeep of its oxygen sensor. People often wonder if tiny components have a small or insignificant role in the overall vehicle’s performance. But that doesn’t seem to be the case. 

O2 sensors keep the exhaust system’s oxygen levels in check and ensure a more efficient and clean engine. Emission tests are one of the ways of telling that your car’s oxygen sensor is going bad. But, numerous other symptoms can help you identify a bad O2 sensor. 

You can identify these symptoms and fix the problem before your car runs into engine troubles and poor fuel combustion. Below is a discussion of all the common symptoms of a bad oxygen sensor. Keep reading! 

How Does an Oxygen Sensor Work? 

It is essential to understand how this tiny device works before we jump to the symptoms. The size of an oxygen sensor is similar to that of a spark plug. The purpose of the oxygen sensor is to keep track of the amount of oxygen in the exhaust. 

The sensor keeps track of how much oxygen is present in the exhaust and compares the results to outside oxygen levels. The sensors forward the results to your car’s system for processing and further adjustments. 

Post this, the car’s engine system will adjust the ratio. The ultimate goal of this process is to help your car run efficiently. Also, O2 sensors work towards preventing toxic emissions and improving gas mileage. Modern vehicles have computerized engines that include sensors to regulate and enhance overall performance. 

As the vehicle’s engine system gathers this information, it adjusts the ratio of oxygen to fuel in the engine. It is an endless loop where the sensors track the oxygen levels in the exhaust and send the readings to the car’s engine system. 

When your car’s O2 sensors malfunction or break, the engine system will inject a rich blend of fuel. When this situation takes place, it’ll increase the fuel consumption of your car. Besides, it’ll also increase the production of carbon in the car. 

exhaust manifold

What Are the 7 Symptoms of a Bad Oxygen Sensor? 

If something is off with your car’s oxygen sensor, the internal combustion system will suffer. Your vehicle will be battling with all sorts of engine drama if it has a bad oxygen sensor. Luckily, most of these symptoms are easy to spot. Here are the seven signs of a failing oxygen sensor you need to watch out for: 

Check Engine Light Blinking 

Blinking engine light is one of the most common symptoms of a failing oxygen sensor. The flashing check engine light indirectly tells you that it’s time to visit the mechanic for a checkup. These sensors can impact fuel and air combustion. 

If the oxygen sensors find that there is less oxygen post-combustion from the exhaust gases, the engine will keep trying to adjust it. Unfortunately, if the oxygen sensor is malfunctioning, the engine system can overlook such problems. Ultimately, it’ll lead your car to poor vehicle performance. 

The car’s engine module will also understand that there is a problem with the engine. Also, this situation can trigger the check engine light. In high-end cars with built-in engine systems, you may spot error codes. The code generally indicates that the O2 sensor is malfunctioning.   

Poor Fuel Economy 

If your car has been suffering from poor fuel economy, the chances are that the oxygen sensor is not working as it should. When your vehicle is consuming fuel abnormally, it’s time to replace the oxygen sensor. Whenever the fuel in the engine is too lean or rich, the fuel combustion efficiency reduces. 

Since the oxygen sensors degrade with time, it gives wrong signals to the systems and you’d notice fuel consumption amount spiking. Your car will burn more fuel than expected which is a sign of poor fuel economy. For this reason, an O2 sensor is an integral part of the vehicle.    

Rough Idling Engine and Misfires

When the car’s oxygen sensors are not working appropriately, it will frequently run roughly and misfire while idling. A bad oxygen sensor comes with several other engine problems, such as engine hesitation, stalling, and power loss. 

As you would have read before, the sensor is responsible for sending information to the car’s engine system. This data helps in combustion intervals and engine timing. In turn, these affect the air to fuel ratio that translates to efficiency in combustion. 

In a nutshell, a poorly working oxygen sensor disturbs the engine system and leads to irregular and rough engine functioning when idle. 

Deteriorated Engine Performance

You can save a lot on automotive repair bills if you spot a lousy oxygen sensor on time. Another O2 sensor failure sign is weakened engine performance. If there is an issue with the combustion process of your car’s engine system, it will eventually lead to a weaker engine. 

You can understand poor engine performance while driving. While driving, if the acceleration seems to stumble, it is a sign of poor engine performance. Your car will not be able to deliver the same performance as before in this case. 

Failing Emissions Test

Another symptom of failing oxygen sensors is the constant failure in emission tests. The O2 sensor is located in the manifold of the exhaust system which allows it to help with emissions control. Some of the states and counties have a rule for vehicles to pass the emission tests. 

These emission tests ensure that your vehicle is not producing carbon dioxide over safe levels. You might not be aware, but the oxygen sensor helps with emission control. As a result, a failed emission test is an indication that your oxygen sensor needs a look! 

Emission of Black Smoke 

Many car owners take the problem of black smoke very lightly. However, most of the time, it signifies something drastic. Black smoke is an indication of improper combustion within the car’s engine system. As you would have read above, an oxygen sensor plays a critical role in sending data to the car’s engine control unit. 

It tells the engine system how to adjust the fuel and air quantities. In any case, oxygen sensors work to prevent emissions. A bad oxygen sensor might not be accurately able to balance the fuel to air ratio. It means that the combustion process will be insufficient. It will ultimately result in black smoke residue. 

Intolerable Rotten Egg Smell 

Is your car lately smelling odd and weird? Naturally, you might not take it as a symptom of a car part failure. But please do know that a broken oxygen sensor could be the cause of that intolerable odor. The rotten egg smell from the faulty oxygen sensor is caused by too much fuel in the engine. 

Excess fuel in the engine is the primary reason behind a sulphuric smell. You might also notice a cloud of black smoke coming out of the exhaust. So, whenever you refill the gas taken, take notes of the frequency and quantity. If your car is out of gas frequently, hire a certified mechanic right away! 

When Should I Replace My Oxygen Sensor?

If you have noticed any of the symptoms, you might be confused if you should replace your oxygen sensor or not. Like other parts of your vehicle, the oxygen sensors might also go through damage. Installing a new oxygen sensor ensures the fuel efficiency and safety of your car.

If your car’s manufacturing dates back to 15 years, you must replace the oxygen sensor every 60,000 to 90,000 miles. An old and deteriorating oxygen sensor might not be able to produce accurate feedback. 

Keeping up with the replacement schedule can help you skip failures and toxic emissions. As soon as you spot any symptom like poor gas mileage or blinking engine light, we recommend you book a checkup with a mechanic.  

fuel mixture

FAQs 

What Can Happen to a Vehicle If It Has a Failing Oxygen Sensor? 

When your car’s oxygen sensor is not working aptly, it might send incorrect feedback to your car’s PCM. In some cases, it might not send any feedback at all. These errors make it difficult for your car to balance the oxygen to fuel ratio. Proper oxygen to fuel ratio is essential for your vehicle to run smoothly. 

As we mentioned earlier, when your car has a bad oxygen sensor, it will experience poor fuel consumption. It might also suffer from misfiring. 

Can a Deteriorating O2 Sensor Lead to Power Loss? 

With a bad O2 sensor, it is natural to fear power loss. Since the faulty oxygen sensor sends incorrect readings, it can lead to inaccurate adjustments in the fuel system and combustion engine’s intake. 

Such a circumstance can trigger inaccurate shifting points. Here, the blend of fuel injected by the engine will be inaccurate. Engine misfires are also a result of inaccurate shifting points. The gas mileage would also be disappointing. It is important to mention that incorrect fuel injection and fuel timing impact fuel combustion. Fuel combustion is also responsible for running your car correctly. Besides, inadequate combustion results in insufficient power for engine functions such as acceleration. 

Does a Bad O2 Sensor Also Cause Sputtering? 

The primary function of your car’s oxygen sensors is to measure how lean or rich the exhaust gases are at the vehicle’s combustion spot. Based on this feedback, the car balances the amount of fuel injected into the engine. 

A failing O2 sensor disturbs the fuel amount in the engine. As a result, your car’s engine might sputter. It would help if you replaced a malfunctioning O2 sensor to restore the correct fuel to air ratio. 

Can I Continue to Drive My Car Even If It Has a Bad O2 Sensor? 

Most of the time, a bad O2 sensor does not pose any danger while driving. The possibility of the car shutting down due to a bad O2 sensor is rare. The purpose of O2 sensors is to send information to the car’s PCM to adjust the air to fuel ratio. 

When those sensors completely fail, the check engine lights will blink. However, you would be able to continue driving the vehicle until the O2 sensor leads to worse problems, ultimately stopping the vehicle. However, we suggest against this.

What is the Cost of Replacing an Oxygen Sensor? 

Different factors affect the oxygen sensor replacement cost. The mechanic labor cost and car model determine the replacement costs. You might have to pay nearly $50 to $100 to install a new oxygen sensor in your car. In addition to that, the mechanic labor costs would be around $150. 

Rates for mechanical labor range from $50 to $150 on an hourly basis. If you have a professional mechanic, you can get the simple job done within 30 minutes.  

Bottom Line 

It would be wise to rush your car to the nearest mechanic as soon as you notice any of these symptoms. Even though you can drive a vehicle with a bad oxygen sensor, your vehicle will struggle to offer premium performance. 

Not only will the engine be less efficient, but you’ll also shell out more for fuel expenses. I also suggest you take your car from time to time to the best mechanic for checkups.  A perfectly working oxygen sensor is suitable for your wallet and the environment! 

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